fix(tables/lua): switch smart_tab/return to <Cmd>, drop vim.schedule

The keymap harness caught a regression in 5b6f789: returning '' from
the <expr> mapping and deferring cursor placement to vim.schedule
breaks any keypress immediately following Tab/<CR>. nvim_feedkeys with
the 'x' flag drains all queued keys synchronously, so the user's next
key lands at the pre-jump cursor position — and the scheduled
callback's startinsert leaks insert mode into the next test.

Mirror what the VimL side already does: have <expr> return
"<Cmd>lua require('nuwiki.commands')._helper(args)<CR>" so the
align + cursor-jump runs synchronously inside the same keypress. No
schedule, no mode juggling.

  cr.adds_new_table_row              ✓
  tab.next_cell_in_table             ✓
  tab.from_first_cell_moves_to_second ✓
  shift_tab.prev_cell_in_table       ✓

39/39 in scripts/test-keymaps.sh (was 35/4-fail).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

lua/nuwiki/commands.lua

@@ -725,49 +725,53 @@ local function align_table_at(row)
   vim.api.nvim_buf_set_lines(0, s - 1, e, false, new_lines)
 end
 
-local function ensure_insert_mode()
-  if vim.api.nvim_get_mode().mode ~= 'i' then
-    vim.cmd('startinsert')
-  end
+-- Public helpers dispatched via `<Cmd>` from the `<expr>` mappings.
+-- The mappings return a `<Cmd>lua require('nuwiki.commands')._foo(…)<CR>`
+-- keystroke so these run synchronously inside the same keypress —
+-- crucial when the user types something *immediately* after Tab/<CR>,
+-- which would otherwise land at the pre-jump cursor (the bug a prior
+-- `vim.schedule`-based version shipped with).
+
+function M._table_jump_to_cell(row, target_idx)
+  align_table_at(row)
+  local new_line = vim.fn.getline(row)
+  local starts = table_cell_starts(new_line)
+  if target_idx < 1 or target_idx >= #starts then return end
+  -- starts[i] is the 1-based byte position of the i-th `|`. Placing the
+  -- cursor at 0-based byte `starts[i]` lands on the space immediately
+  -- after that pipe — the first character inside the cell it opens.
+  vim.api.nvim_win_set_cursor(0, { row, starts[target_idx] })
 end
 
-local function schedule_insert_table_row_below(row)
-  -- After `align_table_at`, the row count of the table containing
-  -- `row` is fixed and `getline(row)` reflects the aligned content.
-  vim.schedule(function()
-    align_table_at(row)
-    local new_line = vim.fn.getline(row)
-    local starts = table_cell_starts(new_line)
-    if #starts < 2 then return end
-    local indent = new_line:match('^(%s*)') or ''
-    local cell_count = #starts - 1
-    local new_row = indent .. '|' .. string.rep('   |', cell_count)
-    vim.api.nvim_buf_set_lines(0, row, row, false, { new_row })
-    vim.api.nvim_win_set_cursor(0, { row + 1, #indent + 1 })
-    ensure_insert_mode()
-  end)
+function M._table_insert_row_below(row)
+  align_table_at(row)
+  local new_line = vim.fn.getline(row)
+  local starts = table_cell_starts(new_line)
+  if #starts < 2 then return end
+  local indent = new_line:match('^(%s*)') or ''
+  local cell_count = #starts - 1
+  local fresh = indent .. '|' .. string.rep('   |', cell_count)
+  vim.api.nvim_buf_set_lines(0, row, row, false, { fresh })
+  vim.api.nvim_win_set_cursor(0, { row + 1, #indent + 1 })
 end
 
 --- Smart `<CR>` for insert mode — vimwiki parity for `:VimwikiReturn`.
 --- Used as an `<expr>` keymap so the function is side-effect-free on
---- the buffer (textlock is active). Non-table branches encode their
---- behaviour as returned keystrokes; the table-row branch schedules a
---- post-textlock callback that aligns the table, inserts a fresh row,
---- and places the cursor inside the new row's first cell.
+--- the buffer (textlock is active). The table-row branch hands off to
+--- `_table_insert_row_below` via `<Cmd>` so the new row is in place
+--- before the user's next keystroke is processed.
 function M.smart_return()
   local line = vim.api.nvim_get_current_line()
   local function tc(s) return vim.api.nvim_replace_termcodes(s, true, false, true) end
   local cr = tc('<CR>')
   local esc = tc('<Esc>')
 
-  -- Table row → align existing rows, then add a fresh empty row below.
-  -- Doing this via `<CR>` + typed row keystrokes would split the
-  -- current line at the cursor and drag the trailing `|` onto the new
-  -- line — so we punt to `vim.schedule` instead.
   if is_table_row(line) then
-    local cur = vim.api.nvim_win_get_cursor(0)
-    schedule_insert_table_row_below(cur[1])
-    return ''
+    local row = vim.api.nvim_win_get_cursor(0)[1]
+    return string.format(
+      '<Cmd>lua require("nuwiki.commands")._table_insert_row_below(%d)<CR>',
+      row
+    )
   end
 
   -- List item with marker?
@@ -814,26 +818,17 @@ function M.smart_tab()
     if start <= col + 1 then current_idx = i end
   end
   local target_idx = current_idx + 1
-
-  vim.schedule(function()
-    align_table_at(row)
-    local new_line = vim.fn.getline(row)
-    local starts = table_cell_starts(new_line)
-    if target_idx < #starts then
-      -- Land at the first space of the target cell (byte position
-      -- equal to the 1-based pipe position).
-      vim.api.nvim_win_set_cursor(0, { row, starts[target_idx] })
-      ensure_insert_mode()
-    else
-      local indent = new_line:match('^(%s*)') or ''
-      local cell_count = math.max(#starts - 1, 1)
-      local new_row = indent .. '|' .. string.rep('   |', cell_count)
-      vim.api.nvim_buf_set_lines(0, row, row, false, { new_row })
-      vim.api.nvim_win_set_cursor(0, { row + 1, #indent + 1 })
-      ensure_insert_mode()
-    end
-  end)
-  return ''
+  if target_idx >= #cell_starts then
+    return string.format(
+      '<Cmd>lua require("nuwiki.commands")._table_insert_row_below(%d)<CR>',
+      row
+    )
+  end
+  return string.format(
+    '<Cmd>lua require("nuwiki.commands")._table_jump_to_cell(%d, %d)<CR>',
+    row,
+    target_idx
+  )
 end
 
 function M.smart_shift_tab()
@@ -853,16 +848,11 @@ function M.smart_shift_tab()
   end
   if not current_idx or current_idx <= 1 then return stab end
   local target_idx = current_idx - 1
-
-  vim.schedule(function()
-    align_table_at(row)
-    local new_line = vim.fn.getline(row)
-    local starts = table_cell_starts(new_line)
-    if target_idx < 1 or target_idx >= #starts then return end
-    vim.api.nvim_win_set_cursor(0, { row, starts[target_idx] })
-    ensure_insert_mode()
-  end)
-  return ''
+  return string.format(
+    '<Cmd>lua require("nuwiki.commands")._table_jump_to_cell(%d, %d)<CR>',
+    row,
+    target_idx
+  )
 end
 
 -- §13.1 Cluster B — table rewriters.