feat(parity): close the entire P3 Commands section

All six remaining command gaps (client-side; no server change):

- VimwikiRenameFile: bare -> -nargs=? (arg accepted-ignored; rename still
  delegates to the LSP rename prompt). No more E488.

- VimwikiVar / NuwikiVar: get/set the client config (upstream vimwiki#vars#cmd).
  No arg prints config (Vim: g:nuwiki_*; Neovim: resolved setup() opts), one arg
  gets a key, two+ sets it. Global command, both clients.

- VimwikiReturn / NuwikiReturn: command form of the smart <CR> continuation —
  enters insert at EOL and fires the <CR> mapping (return_cmd / vimwiki_return).
  Upstream's mode-flag args accepted but unused.

- VimwikiTableAlignQ vs AlignW: corrected — upstream's gqq/gww are identical on
  a table; the only difference is the non-table fallback (native `normal! gqq`
  vs `gww`). New table_align_or_cmd(cmd) aligns on a table row, else runs
  `normal! <cmd>`. Q/gqq/gq1 -> gqq; W/gww/gw1 -> gww; NuwikiTableAlign -> gqq.

- VimwikiSearch / VWS: scope the lvimgrep to the current wiki's root (resolved
  client-side) over <root>/**/*<ext>, not CWD `**`; empty pattern reuses the
  last search. Both clients.

- VimwikiIndex family: add global Vimwiki/NuwikiIndex + TabIndex entry points
  (plugin/nuwiki.vim + init.lua _setup_global_commands, with -count), so a wiki
  opens from any buffer. Buffer-local copies still shadow inside wiki buffers.

Tests: surface.{Vimwiki,Nuwiki}{Return,Var}, cmd.VimwikiVar_sets_*,
cmd.global_entry_points (both harnesses). Docs (README + doc/nuwiki.txt) and the
gap doc updated. Neovim 299, Vim 291/18/21 pass.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lua/nuwiki/commands.lua

@@ -285,6 +285,67 @@ function M.show_version()
   }, false, {})
 end
 
+-- :VimwikiSearch / :VWS {pattern} — search the current wiki's files (upstream
+-- scopes to the wiki, not the editor CWD). Resolves the wiki whose root holds
+-- the current file, else the first configured wiki, else CWD. Empty pattern
+-- reuses the last search. Populates the location list.
+function M.search(args)
+  local pat = (args == nil or args == '') and vim.fn.getreg('/') or args
+  if pat == '' then
+    vim.notify('nuwiki: no search pattern', vim.log.levels.WARN)
+    return
+  end
+  local config = require('nuwiki.config')
+  local file = vim.fn.expand('%:p')
+  local root, ext = '', '.wiki'
+  for _, w in ipairs(config.wiki_list()) do
+    local wroot = vim.fn.fnamemodify(vim.fn.expand(w.root), ':p')
+    if file:sub(1, #wroot) == wroot then
+      root, ext = wroot, w.ext or ext
+      break
+    end
+  end
+  if root == '' then
+    local first = config.wiki_list()[1]
+    if first then
+      root = vim.fn.fnamemodify(vim.fn.expand(first.root), ':p')
+      ext = first.ext or ext
+    end
+  end
+  if not ext:match('^%.') then ext = '.' .. ext end
+  local glob = root == '' and '**' or (vim.fn.fnameescape(root) .. '**/*' .. ext)
+  vim.cmd('lvimgrep /' .. vim.fn.escape(pat, '/') .. '/j ' .. glob)
+  vim.cmd('lopen')
+end
+
+-- :VimwikiVar / :NuwikiVar [key [value]] — get/set the nuwiki client config
+-- (upstream's vimwiki#vars#cmd). No arg prints the resolved setup options; one
+-- arg prints that key; two+ sets it on the in-memory options (server-backed
+-- settings need a restart).
+function M.var(arg)
+  local parts = vim.split(arg or '', '%s+', { trimempty = true })
+  local opts = require('nuwiki.config').options
+  if #parts == 0 then
+    local keys = vim.tbl_keys(opts)
+    table.sort(keys)
+    local lines = {}
+    for _, k in ipairs(keys) do
+      lines[#lines + 1] = { string.format('%s = %s\n', k, vim.inspect(opts[k])) }
+    end
+    vim.api.nvim_echo(lines, false, {})
+    return
+  end
+  local key = parts[1]
+  if #parts == 1 then
+    vim.api.nvim_echo({ { string.format('%s = %s', key, vim.inspect(opts[key])) } }, false, {})
+  else
+    opts[key] = table.concat(parts, ' ', 2)
+    vim.api.nvim_echo({ {
+      string.format('set %s = %s  (restart for server-backed settings)', key, vim.inspect(opts[key])),
+    } }, false, {})
+  end
+end
+
 function M.wiki_ui_select()
   local wikis = require('nuwiki.config').wiki_list()
   if #wikis == 0 then
@@ -935,6 +996,15 @@ function M.smart_return()
   return cr
 end
 
+-- :VimwikiReturn / :NuwikiReturn — the command form of the smart `<CR>`
+-- continuation (upstream's mapping-driven VimwikiReturn). Enters insert at end
+-- of line and triggers the buffer-local `<CR>` mapping (smart_return). Args
+-- mirror upstream's mode flags and are unused (continuation is inferred).
+function M.vimwiki_return()
+  vim.api.nvim_feedkeys(
+    vim.api.nvim_replace_termcodes('A<CR>', true, false, true), 'm', false)
+end
+
 --- Insert-mode `<Tab>` / `<S-Tab>` table navigation — vimwiki parity.
 --- Used as `<expr>` keymaps so we can fall back to a literal `<Tab>` /
 --- `<S-Tab>` when the cursor isn't on a table row. Inside a row both
@@ -1026,6 +1096,17 @@ function M.table_align()
   exec('nuwiki.table.align', pos_args())
 end
 
+-- Upstream `gqq` (AlignQ) / `gww` (AlignW): on a table row, align the table;
+-- otherwise fall back to the native Vim format command (`normal! gqq`/`gww`).
+-- `normal!` bypasses our mapping so there's no recursion.
+function M.table_align_or_cmd(cmd)
+  if is_table_row(vim.api.nvim_get_current_line()) then
+    M.table_align()
+  else
+    vim.cmd('normal! ' .. cmd)
+  end
+end
+
 function M.table_move_column_left()
   local p = pos_args()[1]
   p.dir = 'left'