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>

lua/nuwiki/commands.lua

@@ -247,30 +247,29 @@ function M.wiki_tab_index(count)
   end)
 end
 
+-- Pick a wiki and open its index. The list is read straight from config
+-- (no LSP round-trip) so this works from any buffer before a wiki file is
+-- ever opened; opening the index then auto-starts the server.
 function M.wiki_ui_select()
-  exec('nuwiki.wiki.select', { {} }, function(r)
-    if type(r) ~= 'table' or #r == 0 then
-      vim.notify('nuwiki: no wikis configured')
-      return
+  local wikis = require('nuwiki.config').wiki_list()
+  if #wikis == 0 then
+    vim.notify('nuwiki: no wikis configured', vim.log.levels.WARN)
+    return
+  end
+  vim.ui.select(
+    wikis,
+    {
+      prompt = 'Select a wiki',
+      format_item = function(w)
+        return string.format('%s  (%s)', w.name, w.root)
+      end,
+    },
+    function(choice)
+      if not choice then return end
+      local path = choice.root .. '/' .. choice.idx .. choice.ext
+      vim.cmd('edit ' .. vim.fn.fnameescape(vim.fn.expand(path)))
     end
-    vim.ui.select(
-      r,
-      {
-        prompt = 'Pick a wiki',
-        format_item = function(w)
-          return string.format('%d. %s  (%s)', (w.id or 0) + 1, w.name or '?', tostring(w.root))
-        end,
-      },
-      function(choice)
-        if not choice then return end
-        exec(
-          'nuwiki.wiki.openIndex',
-          { { wiki = choice.id } },
-          function(rr) if rr and rr.uri then open_uri(rr.uri) end end
-        )
-      end
-    )
-  end)
+  )
 end
 
 function M.wiki_goto_page(name)