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>

autoload/nuwiki/commands.vim

@@ -175,6 +175,66 @@ function! nuwiki#commands#show_version() abort
   echo (has('nvim') ? 'Neovim' : 'Vim') . ': ' . v:version
 endfunction
 
+" :VimwikiSearch / :VWS {pattern} — search the current wiki's files (upstream's
+" search scopes to the wiki, not the editor's CWD). Resolves the wiki whose root
+" contains the current file; falls back to the first configured wiki, then to
+" the CWD. An empty pattern reuses the last search (`@/`). Populates the
+" location list.
+function! nuwiki#commands#search(args) abort
+  let l:pat = a:args ==# '' ? @/ : a:args
+  if l:pat ==# ''
+    echohl WarningMsg | echom 'nuwiki: no search pattern' | echohl None
+    return
+  endif
+  " Resolve { root, ext } for the current buffer's wiki.
+  let l:file = expand('%:p')
+  let l:root = ''
+  let l:ext = get(g:, 'nuwiki_file_extension', '.wiki')
+  for l:w in nuwiki#commands#wiki_list()
+    let l:wroot = fnamemodify(expand(l:w.root), ':p')
+    if l:file[: len(l:wroot) - 1] ==# l:wroot
+      let l:root = l:wroot
+      let l:ext = get(l:w, 'ext', l:ext)
+      break
+    endif
+  endfor
+  if l:root ==# '' && !empty(nuwiki#commands#wiki_list())
+    let l:first = nuwiki#commands#wiki_list()[0]
+    let l:root = fnamemodify(expand(l:first.root), ':p')
+    let l:ext = get(l:first, 'ext', l:ext)
+  endif
+  let l:ext = l:ext[0] ==# '.' ? l:ext : '.' . l:ext
+  let l:glob = l:root ==# '' ? '**' : fnameescape(l:root) . '**/*' . l:ext
+  execute 'lvimgrep /' . escape(l:pat, '/') . '/j ' . l:glob
+  lopen
+endfunction
+
+" :VimwikiVar / :NuwikiVar [key [value]] — get/set the nuwiki client globals
+" (g:nuwiki_*), mirroring upstream's vimwiki#vars#cmd. No arg prints every
+" g:nuwiki_* var; one arg prints that var; two+ sets it (as a string — server-
+" backed settings need a restart to take effect, which we note).
+function! nuwiki#commands#var(arg) abort
+  let l:parts = split(a:arg, '\s\+')
+  if empty(l:parts)
+    let l:keys = sort(filter(keys(g:), 'v:val =~# "^nuwiki_"'))
+    if empty(l:keys)
+      echo 'nuwiki: no g:nuwiki_* variables set'
+      return
+    endif
+    for l:k in l:keys
+      echo printf('g:%s = %s', l:k, string(g:[l:k]))
+    endfor
+    return
+  endif
+  let l:key = 'nuwiki_' . substitute(l:parts[0], '^nuwiki_', '', '')
+  if len(l:parts) == 1
+    echo printf('g:%s = %s', l:key, exists('g:' . l:key) ? string(g:[l:key]) : '(unset)')
+  else
+    let g:[l:key] = join(l:parts[1:], ' ')
+    echo printf('set g:%s = %s  (restart for server-backed settings)', l:key, string(g:[l:key]))
+  endif
+endfunction
+
 function! nuwiki#commands#wiki_ui_select() abort
   let l:wikis = nuwiki#commands#wiki_list()
   if empty(l:wikis)
@@ -929,6 +989,18 @@ function! nuwiki#commands#table_align() abort
   call s:exec('nuwiki.table.align', l:args)
 endfunction
 
+" Upstream `gqq` (AlignQ) / `gww` (AlignW): on a table row, align the table;
+" otherwise fall back to the native Vim format command (`normal! gqq` keeps the
+" cursor free; `gww` keeps the cursor in place). `normal!` bypasses our own
+" mapping so there's no recursion.
+function! nuwiki#commands#table_align_or_cmd(cmd) abort
+  if s:is_table_row(getline('.'))
+    call nuwiki#commands#table_align()
+  else
+    execute 'normal! ' . a:cmd
+  endif
+endfunction
+
 function! nuwiki#commands#table_move_left() abort
   let l:p = s:cursor_position()
   let l:args = [{
@@ -1233,6 +1305,15 @@ function! nuwiki#commands#smart_return() abort
   return "\<CR>"
 endfunction
 
+" :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),
+" continuing the list item / table row. Args mirror upstream's mode flags and
+" are accepted but unused (the continuation is inferred from the line).
+function! nuwiki#commands#return_cmd(...) abort
+  call feedkeys("A\<CR>", 'm')
+endfunction
+
 " Insert-mode `<Tab>` / `<S-Tab>` table navigation — vimwiki parity.
 " Used as `<expr>` mappings so we can pass `<Tab>` / `<S-Tab>` through
 " verbatim when the cursor isn't on a table row.