feat: opt-in Journal search page and JournalSearchBox

- journal.routes.search (off by default) registers journal-search, the
  results page for ?q= in the API's relevance order (no sort is sent),
  server-rendered with a Polish-aware result count.
- JournalSearchBox: an icon button and a WAI-ARIA combobox with debounced
  ?fields=suggest suggestions, stale answers dropped, query words marked
  ignoring diacritics; a plain GET form without JS.
- The module keeps the search path out of the route cache and the sitemap
  and marks it noindex, follow.
- Client: suggestPosts and the fields option; useJournalLinks.searchLink.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "vue-journal-layer",
-  "version": "0.6.0",
+  "version": "0.7.0",
   "private": true,
   "type": "module",
   "main": "./nuxt.config.ts",