build: replace luacheck with selene, add nix devshell and pre-commit (#20)

* build: replace luacheck with selene

Problem: luacheck is unmaintained (last release 2018) and required
suppressing four warning classes to avoid false positives. It also
lacks first-class vim/neovim awareness.

Solution: switch to selene with std='vim' for vim-aware linting.
Replace the luacheck CI job with selene, update the Makefile lint
target, and delete .luacheckrc.

* build: add nix devshell and pre-commit hooks

Problem: oil.nvim had no reproducible dev environment. The .envrc
set up a Python venv for the now-removed docgen pipeline, and there
were no pre-commit hooks for local formatting checks.

Solution: add flake.nix with stylua, selene, and prettier in the
devshell. Replace the stale Python .envrc with 'use flake'. Add
.pre-commit-config.yaml with stylua and prettier hooks matching
other plugins in the repo collection.

* fix: format with stylua

* build(selene): configure lints and add inline suppressions

Problem: selene fails on 5 errors and 3 warnings from upstream code
patterns that are intentional (mixed tables in config API, unused
callback parameters, identical if branches for readability).

Solution: globally allow mixed_table and unused_variable (high volume,
inherent to the codebase design). Add inline selene:allow directives
for the 8 remaining issues: if_same_then_else (4), mismatched_arg_count
(1), empty_if (2), global_usage (1). Remove .envrc from tracking.

* build: switch typecheck action to mrcjkb/lua-typecheck-action

Problem: oil.nvim used stevearc/nvim-typecheck-action, which required
cloning the action repo locally for the Makefile lint target. All
other plugins in the collection use mrcjkb/lua-typecheck-action.

Solution: swap to mrcjkb/lua-typecheck-action@v0 for consistency.
Remove the nvim-typecheck-action git clone from the Makefile and
.gitignore. Drop LuaLS from the local lint target since it requires
a full language server install — CI handles it.

lua/oil/config.lua

@@ -5,7 +5,7 @@ local default_config = {
   -- Id is automatically added at the beginning, and name at the end
   -- See :help oil-columns
   columns = {
-    "icon",
+    'icon',
     -- "permissions",
     -- "size",
     -- "mtime",
@@ -13,18 +13,18 @@ local default_config = {
   -- Buffer-local options to use for oil buffers
   buf_options = {
     buflisted = false,
-    bufhidden = "hide",
+    bufhidden = 'hide',
   },
   -- Window-local options to use for oil buffers
   win_options = {
     wrap = false,
-    signcolumn = "no",
+    signcolumn = 'no',
     cursorcolumn = false,
-    foldcolumn = "0",
+    foldcolumn = '0',
     spell = false,
     list = false,
     conceallevel = 3,
-    concealcursor = "nvic",
+    concealcursor = 'nvic',
   },
   -- Send deleted files to the trash instead of permanently deleting them (:help oil-trash)
   delete_to_trash = false,
@@ -48,7 +48,7 @@ local default_config = {
   },
   -- Constrain the cursor to the editable parts of the oil buffer
   -- Set to `false` to disable, or "name" to keep it on the file names
-  constrain_cursor = "editable",
+  constrain_cursor = 'editable',
   -- Set to true to watch the filesystem for changes and reload oil
   watch_for_changes = false,
   -- Keymaps in oil buffer. Can be any value that `vim.keymap.set` accepts OR a table of keymap
@@ -58,22 +58,22 @@ local default_config = {
   -- Set to `false` to remove a keymap
   -- See :help oil-actions for a list of all available actions
   keymaps = {
-    ["g?"] = { "actions.show_help", mode = "n" },
-    ["<CR>"] = "actions.select",
-    ["<C-s>"] = { "actions.select", opts = { vertical = true } },
-    ["<C-h>"] = { "actions.select", opts = { horizontal = true } },
-    ["<C-t>"] = { "actions.select", opts = { tab = true } },
-    ["<C-p>"] = "actions.preview",
-    ["<C-c>"] = { "actions.close", mode = "n" },
-    ["<C-l>"] = "actions.refresh",
-    ["-"] = { "actions.parent", mode = "n" },
-    ["_"] = { "actions.open_cwd", mode = "n" },
-    ["`"] = { "actions.cd", mode = "n" },
-    ["g~"] = { "actions.cd", opts = { scope = "tab" }, mode = "n" },
-    ["gs"] = { "actions.change_sort", mode = "n" },
-    ["gx"] = "actions.open_external",
-    ["g."] = { "actions.toggle_hidden", mode = "n" },
-    ["g\\"] = { "actions.toggle_trash", mode = "n" },
+    ['g?'] = { 'actions.show_help', mode = 'n' },
+    ['<CR>'] = 'actions.select',
+    ['<C-s>'] = { 'actions.select', opts = { vertical = true } },
+    ['<C-h>'] = { 'actions.select', opts = { horizontal = true } },
+    ['<C-t>'] = { 'actions.select', opts = { tab = true } },
+    ['<C-p>'] = 'actions.preview',
+    ['<C-c>'] = { 'actions.close', mode = 'n' },
+    ['<C-l>'] = 'actions.refresh',
+    ['-'] = { 'actions.parent', mode = 'n' },
+    ['_'] = { 'actions.open_cwd', mode = 'n' },
+    ['`'] = { 'actions.cd', mode = 'n' },
+    ['g~'] = { 'actions.cd', opts = { scope = 'tab' }, mode = 'n' },
+    ['gs'] = { 'actions.change_sort', mode = 'n' },
+    ['gx'] = 'actions.open_external',
+    ['g.'] = { 'actions.toggle_hidden', mode = 'n' },
+    ['g\\'] = { 'actions.toggle_trash', mode = 'n' },
   },
   -- Set to false to disable all of the above keymaps
   use_default_keymaps = true,
@@ -82,7 +82,7 @@ local default_config = {
     show_hidden = false,
     -- This function defines what is considered a "hidden" file
     is_hidden_file = function(name, bufnr)
-      local m = name:match("^%.")
+      local m = name:match('^%.')
       return m ~= nil
     end,
     -- This function defines what will never be shown, even when `show_hidden` is set
@@ -91,14 +91,14 @@ local default_config = {
     end,
     -- Sort file names with numbers in a more intuitive order for humans.
     -- Can be "fast", true, or false. "fast" will turn it off for large directories.
-    natural_order = "fast",
+    natural_order = 'fast',
     -- Sort file and directory names case insensitive
     case_insensitive = false,
     sort = {
       -- sort order can be "asc" or "desc"
       -- see :help oil-columns to see which columns are sortable
-      { "type", "asc" },
-      { "name", "asc" },
+      { 'type', 'asc' },
+      { 'name', 'asc' },
     },
     -- Customize the highlight group for the file name
     highlight_filename = function(entry, is_hidden, is_link_target, is_link_orphan)
@@ -138,7 +138,7 @@ local default_config = {
     -- optionally override the oil buffers window title with custom function: fun(winid: integer): string
     get_win_title = nil,
     -- preview_split: Split direction: "auto", "left", "right", "above", "below".
-    preview_split = "auto",
+    preview_split = 'auto',
     -- This is the config that will be passed to nvim_open_win.
     -- Change values here to customize the layout
     override = function(conf)
@@ -150,7 +150,7 @@ local default_config = {
     -- Whether the preview window is automatically updated when the cursor is moved
     update_on_cursor_moved = true,
     -- How to open the preview window "load"|"scratch"|"fast_scratch"
-    preview_method = "fast_scratch",
+    preview_method = 'fast_scratch',
     -- A function that returns true to disable preview on a file e.g. to avoid lag
     disable_preview = function(filename)
       return false
@@ -190,7 +190,7 @@ local default_config = {
     min_height = { 5, 0.1 },
     height = nil,
     border = nil,
-    minimized_border = "none",
+    minimized_border = 'none',
     win_options = {
       winblend = 0,
     },
@@ -211,12 +211,12 @@ local default_config = {
 
 -- not "oil-s3://" on older neovim versions, since it doesn't open buffers correctly with a number
 -- in the name
-local oil_s3_string = vim.fn.has("nvim-0.12") == 1 and "oil-s3://" or "oil-sss://"
+local oil_s3_string = vim.fn.has('nvim-0.12') == 1 and 'oil-s3://' or 'oil-sss://'
 default_config.adapters = {
-  ["oil://"] = "files",
-  ["oil-ssh://"] = "ssh",
-  [oil_s3_string] = "s3",
-  ["oil-trash://"] = "trash",
+  ['oil://'] = 'files',
+  ['oil-ssh://'] = 'ssh',
+  [oil_s3_string] = 's3',
+  ['oil-trash://'] = 'trash',
 }
 default_config.adapter_aliases = {}
 -- We want the function in the default config for documentation generation, but if we nil it out
@@ -408,7 +408,7 @@ local M = {}
 M.setup = function(opts)
   opts = opts or vim.g.oil or {}
 
-  local new_conf = vim.tbl_deep_extend("keep", opts, default_config)
+  local new_conf = vim.tbl_deep_extend('keep', opts, default_config)
   if not new_conf.use_default_keymaps then
     new_conf.keymaps = opts.keymaps or {}
   elseif opts.keymaps then
@@ -429,19 +429,19 @@ M.setup = function(opts)
   end
 
   -- Backwards compatibility for old versions that don't support winborder
-  if vim.fn.has("nvim-0.11") == 0 then
-    new_conf = vim.tbl_deep_extend("keep", new_conf, {
-      float = { border = "rounded" },
-      confirmation = { border = "rounded" },
-      progress = { border = "rounded" },
-      ssh = { border = "rounded" },
-      keymaps_help = { border = "rounded" },
+  if vim.fn.has('nvim-0.11') == 0 then
+    new_conf = vim.tbl_deep_extend('keep', new_conf, {
+      float = { border = 'rounded' },
+      confirmation = { border = 'rounded' },
+      progress = { border = 'rounded' },
+      ssh = { border = 'rounded' },
+      keymaps_help = { border = 'rounded' },
     })
   end
 
   -- Backwards compatibility. We renamed the 'preview' window config to be called 'confirmation'.
   if opts.preview and not opts.confirmation then
-    new_conf.confirmation = vim.tbl_deep_extend("keep", opts.preview, default_config.confirmation)
+    new_conf.confirmation = vim.tbl_deep_extend('keep', opts.preview, default_config.confirmation)
   end
   -- Backwards compatibility. We renamed the 'preview' config to 'preview_win'
   if opts.preview and opts.preview.update_on_cursor_moved ~= nil then
@@ -452,7 +452,7 @@ M.setup = function(opts)
     new_conf.lsp_file_methods.autosave_changes = new_conf.lsp_rename_autosave
     new_conf.lsp_rename_autosave = nil
     vim.notify_once(
-      "oil config value lsp_rename_autosave has moved to lsp_file_methods.autosave_changes.\nCompatibility will be removed on 2024-09-01.",
+      'oil config value lsp_rename_autosave has moved to lsp_file_methods.autosave_changes.\nCompatibility will be removed on 2024-09-01.',
       vim.log.levels.WARN
     )
   end
@@ -479,10 +479,10 @@ M.get_adapter_by_scheme = function(scheme)
   if not scheme then
     return nil
   end
-  if not vim.endswith(scheme, "://") then
-    local pieces = vim.split(scheme, "://", { plain = true })
+  if not vim.endswith(scheme, '://') then
+    local pieces = vim.split(scheme, '://', { plain = true })
     if #pieces <= 2 then
-      scheme = pieces[1] .. "://"
+      scheme = pieces[1] .. '://'
     else
       error(string.format("Malformed url: '%s'", scheme))
     end
@@ -494,7 +494,7 @@ M.get_adapter_by_scheme = function(scheme)
       return nil
     end
     local ok
-    ok, adapter = pcall(require, string.format("oil.adapters.%s", name))
+    ok, adapter = pcall(require, string.format('oil.adapters.%s', name))
     if ok then
       adapter.name = name
       M._adapter_by_scheme[scheme] = adapter