fix(wiki): build wiki picker list from config so it works before opening a file

The picker fetched the wiki list via workspace/executeCommand, but the LSP
only starts once a vimwiki buffer exists — so a wiki could not be selected
until one was already open (chicken-and-egg). Read the list straight from
config instead (g:nuwiki_wikis / scalar fallback, the same source as
open_wiki_path) and open the chosen index directly; that auto-starts the
server via the FileType autocmd.

- Vim: new public nuwiki#commands#wiki_list(); wiki_ui_select() uses it +
  inputlist() + :edit. Global :VimwikiUISelect / :NuwikiUISelect commands.
- Neovim: config.wiki_cfg(n) + config.wiki_list() (init.lua delegates);
  commands.wiki_ui_select() uses them + vim.ui.select + :edit; global
  VimwikiUISelect / NuwikiUISelect user commands registered in setup().

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

scripts/test-keymaps-vim.vim

@@ -321,6 +321,30 @@ call s:record(
       \ 'conceal.cursor_line_revealed_in_normal_mode',
       \ '&l:concealcursor=' . &l:concealcursor)
 
+" ===== Wiki picker (config-driven, no LSP) =====
+
+" The picker builds its list straight from config so it works from any buffer
+" before the LSP (which only starts on a wiki buffer) is running.
+let g:nuwiki_wikis = [
+      \ {'name': 'Personal', 'root': '/tmp/nuwiki-a'},
+      \ {'name': 'Work',     'root': '/tmp/nuwiki-b', 'file_extension': 'md'},
+      \ ]
+let s:wl = nuwiki#commands#wiki_list()
+call s:record(
+      \ len(s:wl) == 2 ? 1 : 0,
+      \ 'wiki_select.lists_all_configured_wikis',
+      \ 'count=' . len(s:wl))
+call s:record(
+      \ get(get(s:wl, 0, {}), 'name', '') ==# 'Personal'
+      \   && get(get(s:wl, 1, {}), 'name', '') ==# 'Work' ? 1 : 0,
+      \ 'wiki_select.preserves_names_and_order',
+      \ 'names=' . string(map(copy(s:wl), 'get(v:val, "name", "")')))
+call s:record(
+      \ get(get(s:wl, 1, {}), 'ext', '') ==# '.md' ? 1 : 0,
+      \ 'wiki_select.honours_per_wiki_extension',
+      \ 'ext=' . get(get(s:wl, 1, {}), 'ext', ''))
+unlet g:nuwiki_wikis
+
 " ===== Wrap up =====
 
 call add(s:results, '')