perf: async cache initialization and remove deepcopy (#8)

* perf: async cache initialization and remove deepcopy

Problem: first completion request blocked the UI with a synchronous
vim.system():wait() call, and every subsequent key completion
unnecessarily deep-copied the entire cache.

Solution: use vim.system with an async callback to initialize the cache
without blocking. Queue pending completion requests during loading and
serve them once parsing finishes. Return cached keys directly instead
of deep-copying.

* fix: revert blanket diagnostics.disable and selene comments

Problem: .luarc.json blanket-disabled four diagnostic categories
project-wide, and selene inline directives were added to suppress
warnings on io.open monkey-patching in tests.

Solution: revert .luarc.json to match main and remove selene comments.

lua/blink-cmp-ghostty.lua

@@ -5,6 +5,9 @@ local M = {}
 local keys_cache = nil
 ---@type table<string, string[]>?
 local enums_cache = nil
+local loading = false
+---@type {ctx: blink.cmp.Context, callback: fun(response: blink.cmp.CompletionResponse)}[]
+local pending = {}
 
 function M.new()
   return setmetatable({}, { __index = M })
@@ -37,14 +40,14 @@ function M.enabled()
   return false
 end
 
+---@param stdout string
 ---@return blink.cmp.CompletionItem[]
-local function parse_keys()
+local function parse_keys(stdout)
   local Kind = require('blink.cmp.types').CompletionItemKind
-  local result = vim.system({ 'ghostty', '+show-config', '--docs' }):wait()
   local items = {}
   local doc_lines = {}
 
-  for line in ((result.stdout or '') .. '\n'):gmatch('(.-)\n') do
+  for line in (stdout .. '\n'):gmatch('(.-)\n') do
     if line:match('^#') then
       local stripped = line:gsub('^# ?', '')
       doc_lines[#doc_lines + 1] = stripped
@@ -101,13 +104,10 @@ end
 
 ---@param ctx blink.cmp.Context
 ---@param callback fun(response: blink.cmp.CompletionResponse)
----@return fun()
-function M:get_completions(ctx, callback)
+local function respond(ctx, callback)
   if not keys_cache or not enums_cache then
-    keys_cache = parse_keys()
-    enums_cache = parse_enums()
+    return
   end
-
   local line = ctx.line
   local col = ctx.cursor[2]
   local eq_pos = line:find('=')
@@ -130,16 +130,42 @@ function M:get_completions(ctx, callback)
         is_incomplete_backward = false,
         items = items,
       })
-      return function() end
+      return
     end
     callback({ items = {} })
   else
     callback({
       is_incomplete_forward = false,
       is_incomplete_backward = false,
-      items = vim.deepcopy(keys_cache),
+      items = keys_cache,
     })
   end
+end
+
+---@param ctx blink.cmp.Context
+---@param callback fun(response: blink.cmp.CompletionResponse)
+---@return fun()
+function M:get_completions(ctx, callback)
+  if keys_cache then
+    respond(ctx, callback)
+    return function() end
+  end
+
+  pending[#pending + 1] = { ctx = ctx, callback = callback }
+  if not loading then
+    loading = true
+    vim.system({ 'ghostty', '+show-config', '--docs' }, {}, function(result)
+      vim.schedule(function()
+        keys_cache = parse_keys(result.stdout or '')
+        enums_cache = parse_enums()
+        loading = false
+        for _, p in ipairs(pending) do
+          respond(p.ctx, p.callback)
+        end
+        pending = {}
+      end)
+    end)
+  end
   return function() end
 end