fix(parity): fifth-pass re-audit — VimwikiGoto nargs, autowriteall, table_auto_fmt

Closes the actionable fifth-pass findings (gap doc updated):

- VimwikiGoto / NuwikiGoto: -nargs=1 -> -nargs=* in all four defs. Was a
  real bug — `:VimwikiGoto` raised E471, `:VimwikiGoto My Page` raised E488,
  and the handler's empty-arg prompt fallback was unreachable. Both clients
  already prompt on empty, so -nargs=* (keeping -complete=pages) restores
  upstream behavior.

- autowriteall (upstream default ON): while a wiki buffer is current, mirror
  Vim's global 'autowriteall' (auto-save on page switch / :make), restoring
  the prior value on leave. Neovim via ftplugin.lua setup_autowriteall
  (BufEnter/BufLeave) gated by the `autowriteall` setup option; Vim via the
  NuwikiAutoWriteAll augroup gated by g:nuwiki_autowriteall.

- table_auto_fmt (upstream default ON): re-align the table under the cursor
  on InsertLeave. Both clients, gated by `table_auto_fmt` / g:nuwiki_table_auto_fmt,
  guarded on the cursor line containing `|` before the async table_align.

Also logged (no code): VimwikiRenameFile missing -nargs=? (subsumed by the
LSP-rename divergence), table_reduce_last_col, user_htmls, hl_headers/
hl_cb_checked, and a commentstring value-mismatch note. Mappings audit clean.

The Neovim harness disables table_auto_fmt in setup (its async re-align would
perturb the deterministic table-nav keystroke cases); its wiring is verified
on a throwaway scratch buffer instead. Docs (README + doc/nuwiki.txt) updated.
Tests: cmd.VimwikiGoto_accepts_multiword, config.autowriteall_applied,
config.table_auto_fmt_autocmd. Neovim 293, Vim 285/18/21 pass.

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

development/tests/test-keymaps.lua

@@ -255,6 +255,34 @@ vim.defer_fn(function()
     end
   end
 
+  -- ===== Config-driven buffer behaviors =====
+  -- autowriteall (default on) mirrors into Vim's global 'autowriteall' while
+  -- the wiki buffer is current.
+  record(vim.o.autowriteall == true, 'config.autowriteall_applied',
+    vim.o.autowriteall and '' or 'autowriteall not set on the wiki buffer')
+  -- table_auto_fmt wiring: with the option enabled, attaching a buffer
+  -- registers a buffer-local InsertLeave autocmd. (It's off in the harness
+  -- setup so the async re-align doesn't perturb the table-nav cases below, so
+  -- verify on a throwaway scratch buffer in its own window.)
+  do
+    local cfg = require('nuwiki.config')
+    cfg.options.table_auto_fmt = true
+    vim.cmd('new')
+    local sbuf = vim.api.nvim_get_current_buf()
+    require('nuwiki.ftplugin').attach(sbuf)
+    local found = false
+    for _, a in ipairs(vim.api.nvim_get_autocmds({ event = 'InsertLeave', buffer = sbuf })) do
+      if a.group_name and a.group_name:match('^nuwiki_taf_') then
+        found = true
+        break
+      end
+    end
+    record(found, 'config.table_auto_fmt_autocmd',
+      found and '' or 'attach did not register the InsertLeave autocmd when enabled')
+    cfg.options.table_auto_fmt = false
+    vim.cmd('bwipeout!')
+  end
+
   -- ===== Lists =====
 
   run('list.toggle_via_C-Space', {