refactor(init): remove help popup, use config-driven keymaps

Problem: Buffer-local keymaps were hardcoded with no way for users to
customize them. The g? help popup duplicated information already in the
vimdoc.

Solution: Remove show_help() and the g? mapping. Refactor
_setup_buf_mappings to read from cfg.keymaps, letting users override or
disable any buffer-local binding via vim.g.pending.

lua/pending/init.lua

@@ -50,37 +50,44 @@ end
 
 ---@param bufnr integer
 function M._setup_buf_mappings(bufnr)
+  local cfg = require('pending.config').get()
+  local km = cfg.keymaps
   local opts = { buffer = bufnr, silent = true }
-  vim.keymap.set('n', 'q', function()
-    buffer.close()
-  end, opts)
-  vim.keymap.set('n', '<Esc>', function()
-    buffer.close()
-  end, opts)
-  vim.keymap.set('n', '<CR>', function()
-    M.toggle_complete()
-  end, opts)
-  vim.keymap.set('n', '<Tab>', function()
-    buffer.toggle_view()
-  end, opts)
-  vim.keymap.set('n', 'g?', function()
-    M.show_help()
-  end, opts)
-  vim.keymap.set('n', '!', function()
-    M.toggle_priority()
-  end, opts)
-  vim.keymap.set('n', 'D', function()
-    M.prompt_date()
-  end, opts)
-  vim.keymap.set('n', 'U', function()
-    M.undo_write()
-  end, opts)
-  vim.keymap.set('n', 'o', function()
-    buffer.open_line(false)
-  end, opts)
-  vim.keymap.set('n', 'O', function()
-    buffer.open_line(true)
-  end, opts)
+
+  ---@type table<string, fun()>
+  local actions = {
+    close = function()
+      buffer.close()
+    end,
+    toggle = function()
+      M.toggle_complete()
+    end,
+    view = function()
+      buffer.toggle_view()
+    end,
+    priority = function()
+      M.toggle_priority()
+    end,
+    date = function()
+      M.prompt_date()
+    end,
+    undo = function()
+      M.undo_write()
+    end,
+    open_line = function()
+      buffer.open_line(false)
+    end,
+    open_line_above = function()
+      buffer.open_line(true)
+    end,
+  }
+
+  for name, fn in pairs(actions) do
+    local key = km[name]
+    if key and key ~= false then
+      vim.keymap.set('n', key --[[@as string]], fn, opts)
+    end
+  end
 end
 
 ---@param bufnr integer
@@ -334,75 +341,6 @@ function M.due()
   vim.cmd('copen')
 end
 
-function M.show_help()
-  local cfg = require('pending.config').get()
-  local dk = cfg.date_syntax or 'due'
-  local rk = cfg.recur_syntax or 'rec'
-  local lines = {
-    'pending.nvim keybindings',
-    '',
-    '<CR>     Toggle complete/uncomplete',
-    '<Tab>    Switch category/priority view',
-    '!        Toggle urgent',
-    'D        Set due date',
-    'U        Undo last write',
-    'o / O    Add new task line',
-    'dd       Delete task line (on :w)',
-    'p / P    Paste (duplicates get new IDs)',
-    'zc / zo  Fold/unfold category (category view)',
-    ':w       Save all changes',
-    '',
-    ':Pending add <text>          Quick-add task',
-    ':Pending add Cat: <text>     Quick-add with category',
-    ':Pending due                 Show overdue/due qflist',
-    ':Pending sync                Push to Google Calendar',
-    ':Pending archive [days]      Purge old done tasks',
-    ':Pending undo                Undo last write',
-    '',
-    'Inline metadata (on new lines before :w):',
-    '  ' .. dk .. ':YYYY-MM-DD    Set due date',
-    '  cat:Name          Set category',
-    '  ' .. rk .. ':pattern       Set recurrence',
-    '',
-    'Due date input:',
-    '  today, tomorrow, yesterday, +Nd, +Nw, +Nm',
-    '  -Nd, -Nw, mon-sun, jan-dec, 1st-31st',
-    '  eod, eow, eom, eoq, eoy, sow, som, soq, soy',
-    '  later, someday',
-    '  Empty input clears due date',
-    '',
-    'Recurrence patterns:',
-    '  daily, weekdays, weekly, biweekly',
-    '  monthly, quarterly, yearly, Nd, Nw, Nm, Ny',
-    '  Prefix ! for completion-based (e.g. !weekly)',
-    '',
-    'Completion: <C-x><C-o> after due:, cat:, rec:',
-    '',
-    'Press q or <Esc> to close',
-  }
-  local buf = vim.api.nvim_create_buf(false, true)
-  vim.api.nvim_buf_set_lines(buf, 0, -1, false, lines)
-  vim.bo[buf].modifiable = false
-  vim.bo[buf].bufhidden = 'wipe'
-  local width = 54
-  local height = #lines
-  local win = vim.api.nvim_open_win(buf, true, {
-    relative = 'editor',
-    width = width,
-    height = height,
-    col = math.floor((vim.o.columns - width) / 2),
-    row = math.floor((vim.o.lines - height) / 2),
-    style = 'minimal',
-    border = 'rounded',
-  })
-  vim.keymap.set('n', 'q', function()
-    vim.api.nvim_win_close(win, true)
-  end, { buffer = buf, silent = true })
-  vim.keymap.set('n', '<Esc>', function()
-    vim.api.nvim_win_close(win, true)
-  end, { buffer = buf, silent = true })
-end
-
 ---@param args string
 function M.command(args)
   if not args or args == '' then