feat(parity): P3 quick-wins — ShowVersion, gLH/gLL/gLR, Search/Align nargs

Closes four low-risk P3 parity items (gap doc updated):

- VimwikiShowVersion / NuwikiShowVersion: new global command (both clients)
  echoing g:nuwiki_version (0.1.0) + the host editor, via
  nuwiki#commands#show_version / commands.show_version.

- gLH / gLL / gLR: upstream's case-variant aliases of gLh/gLl/gLr (dedent /
  indent whole item, renumber all lists) added in both clients.

- VimwikiSearch / VWS: -nargs=1 -> -nargs=* (Vim + Neovim), so a multi-word
  search no longer raises E488 and an empty invocation reuses the last search
  pattern. (The lvimgrep-vs-vimwiki-engine difference stays open.)

- VimwikiTableAlignQ / AlignW / NuwikiTableAlign: bare -> -nargs=?, so
  `:VimwikiTableAlignQ 2` no longer raises E488 (optional column arg is
  accepted-and-ignored; the gqq-align vs gww-align-without-resize split
  stays open).

Docs (doc/nuwiki.txt + README) updated for the command and the aliases.
Tests: surface.{Vimwiki,Nuwiki}ShowVersion, map[n].gL{H,L,R} (both
harnesses), cmd.search_and_tablealign_nargs (vim). Neovim 291, Vim
282/18/21 pass.

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

development/tests/test-keymaps-vim.vim

@@ -112,7 +112,7 @@ let s:both_forms = [
       \ 'RebuildTags', '2HTML', '2HTMLBrowse', 'All2HTML', 'Rss',
       \ 'NormalizeLink', 'RenumberList', 'RenumberAllLists',
       \ 'ListToggle', 'IncrementListItem', 'DecrementListItem',
-      \ 'CatUrl',
+      \ 'CatUrl', 'ShowVersion',
       \ ]
 for s:suffix in s:both_forms
   for s:prefix in ['Nuwiki', 'Vimwiki']
@@ -189,6 +189,7 @@ let s:mapping_surface = [
       \ ['<C-Space>', 'nx'], ['<C-@>', 'nx'], ['<Nul>', 'nx'],
       \ ['gnt', 'n'], ['gln', 'nx'], ['glp', 'nx'], ['glx', 'nx'],
       \ ['glh', 'n'], ['gll', 'n'], ['gLh', 'n'], ['gLl', 'n'],
+      \ ['gLH', 'n'], ['gLL', 'n'], ['gLR', 'n'],
       \ ['glr', 'n'], ['gLr', 'n'], ['gl', 'n'], ['gL', 'n'],
       \ ['gl-', 'n'], ['gL-', 'n'], ['gl*', 'n'], ['gL*', 'n'],
       \ ['gl#', 'n'], ['gL#', 'n'], ['gl1', 'n'], ['gL1', 'n'],
@@ -669,6 +670,28 @@ call s:record(
       \ 'cmd.VimwikiListChangeLvl_accepts_range_and_args',
       \ 'err=' . s:lcl_err)
 
+" ===== :VimwikiSearch / VWS -nargs=* + :VimwikiTableAlignQ/W -nargs=? =====
+" Upstream attributes: Search/VWS take -nargs=* (was -nargs=1, so a multi-word
+" `:VimwikiSearch foo bar` raised E488); TableAlignQ/W take -nargs=? (were bare,
+" so `:VimwikiTableAlignQ 2` raised E488). lvimgrep/align run for real here, so
+" swallow any non-attribute error and assert only that E488 is gone.
+let s:attr_err = ''
+try
+  silent! VimwikiSearch foo bar
+  silent! VWS foo bar
+  silent! VimwikiTableAlignQ 2
+  silent! VimwikiTableAlignW 2
+  silent! NuwikiTableAlign 2
+catch /E488/
+  let s:attr_err = v:exception
+catch
+  " runtime errors (no match, empty table, …) are expected and fine here.
+endtry
+call s:record(
+      \ s:attr_err ==# '' ? 1 : 0,
+      \ 'cmd.search_and_tablealign_nargs',
+      \ 'err=' . s:attr_err)
+
 " ===== :VimwikiRemoveDone -bang -range =====
 " Upstream is `-range`; nuwiki had `-bang` only, so `:'<,'>VimwikiRemoveDone`
 " raised E481. Now `-bang -range`: a ranged invocation must parse (no E481),