feat(commands): VimwikiTable -nargs=* + Index/TabIndex -count=0 (P3 parity)

Two command-attribute parity fixes (audited against upstream vimwiki master):

- VimwikiTable / NuwikiTable were -nargs=1 and called table_insert() with no
  args, so `:VimwikiTable 4 3` raised E488 and cols/rows were unreachable.
  All four defs (Vim+Neovim × Vimwiki+Nuwiki) are now -nargs=* and forward
  <f-args>; the backing table_insert already parsed cols (a:1) + rows (a:2).

- VimwikiIndex/TabIndex (and Nuwiki forms) switch from bare -count to
  upstream's -count=0. Behavior is unchanged (both default count to 0;
  wiki_index already maps a count to the 1-indexed wiki number) — this just
  matches the upstream declaration exactly.

Tests: cmd.VimwikiTable_passes_cols_and_rows (test-keymaps.lua — asserts a
4-col/3-row table) and cmd.VimwikiTable_accepts_cols_rows (test-keymaps-vim.vim
— no E488). gap doc updated.

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

development/tests/test-keymaps-vim.vim

@@ -632,6 +632,25 @@ unlet g:_nuwiki_target
 " follow_link_drop() request mechanism; its end-to-end coverage is the manual
 " development/start-vim.sh check.
 
+" ===== :VimwikiTable -nargs=* (cols+rows) =====
+" Was -nargs=1, which raised E488 on `:VimwikiTable 4 3`. The table insert
+" itself is an LSP roundtrip (no server in this headless harness), so we only
+" assert the arg parse succeeds — i.e. no E488 trailing-characters error.
+call s:set_buf([''])
+call cursor(1, 1)
+let s:tbl_err = ''
+try
+  silent VimwikiTable 4 3
+catch /E488/
+  let s:tbl_err = v:exception
+catch
+  " A non-E488 error (e.g. no LSP attached) is expected and fine here.
+endtry
+call s:record(
+      \ s:tbl_err ==# '' ? 1 : 0,
+      \ 'cmd.VimwikiTable_accepts_cols_rows',
+      \ 'err=' . s:tbl_err)
+
 " ===== Wrap up =====
 
 call add(s:results, '')