refactor(client): self-review cleanup — dead code, dedup, parity, stale comments

A code-review pass over the VimL + Lua client layers (no behaviour change
beyond the noted parity fixes; full editor harness 10/10):

Lua (lua/nuwiki/):
- commands.lua: drop the dead <0.10 make_position_params pcall/no-arg fallback
  (min is 0.11; no-arg form is itself deprecated) and its stale comment.
- commands.lua: simplify the exec() client dispatch — the metatable/rawget
  dance is gone; always use the non-deprecated colon form client:request() on
  0.11+. (This is the block an external review misread as "critical".)
- commands.lua: extract parse_list_marker() + has_auto_indent() shared by
  smart_return/smart_shift_return; extract word_boundaries() shared by
  wrap_cword_as_wikilink/colorize (and unify the equivalent char classes).
- commands.lua: :Nuwiki search now surfaces real lvimgrep errors instead of
  reporting every failure as "no match" (E480 stays a WARN) — parity with the
  VimL twin's `catch /E480/`.
- keymaps.lua: collapse open_below/above_with_bullet into open_with_bullet(cmd)
  (checkbox prefix preserved for `o` only, as before).
- lsp.lua: normalize the wiki root before the buffer-path prefix compare
  (Windows separators); buf path was already normalized.
- ftplugin.lua: drop the always-true has('nvim-0.11') guard and hoist the
  identical foldmethod/foldtext out of both branches.
- install.lua: use a local `uv` instead of mutating the global vim.uv.

VimL (autoload/nuwiki/):
- commands.vim: refresh a stale comment pointing at the old in-repo
  nuwiki-lsp/src/commands.rs path → the nuwiki-rs server generally.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

autoload/nuwiki/commands.vim

@@ -1153,7 +1153,7 @@ endfunction
 " Mirrors `lua/nuwiki/commands.lua`'s `align_table_at` so plain Vim
 " buffers get the same "tighten columns as cells grow" behaviour the
 " Neovim path enjoys, without needing a vim-lsp roundtrip. Algorithm
-" matches `nuwiki-lsp/src/commands.rs::ops::render_aligned_table` (nuwiki-rs repo).
+" matches the table-alignment logic in the nuwiki-rs server.
 
 function! s:is_table_row(line) abort
   return nuwiki#util#is_table_row(a:line)