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.

lib/journal-module.ts

@@ -16,6 +16,7 @@ const PAGE_FILES: Record<keyof JournalRoutes, string> = {
   category: 'CategoryPage',
   tag: 'TagPage',
   author: 'AuthorPage',
+  search: 'SearchPage',
 }
 
 const pagesDir = fileURLToPath(new URL('../app/journal-pages/', import.meta.url))
@@ -39,7 +40,7 @@ export default defineNuxtModule<JournalModuleOptions>({
   },
   defaults: {
     routes: { ...DEFAULT_JOURNAL_ROUTES },
-    perPage: { index: 9, category: 9, tag: 9, author: 9 },
+    perPage: { index: 9, category: 9, tag: 9, author: 9, search: 9 },
     sort: 'published_at desc',
     relatedCount: 3,
     rss: true,
@@ -55,6 +56,21 @@ export default defineNuxtModule<JournalModuleOptions>({
       }
     })
 
+    // The search page renders per ?q, so it is never route-cached: Nitro's
+    // cache keys by path, and an app rule such as '/**': { swr } would serve
+    // one query's results for every query. It is noindex, follow and left
+    // out of the sitemap. The locale-prefixed copies get the same rules. An
+    // app's own rule for the path wins key by key.
+    if (routes.search !== false) {
+      const i18n = (nuxt.options as { i18n?: { locales?: unknown } }).i18n
+      const paths = [routes.search, ...enabledLocaleCodes(i18n?.locales).map((code) => `/${code}${routes.search}`)]
+      const options = nuxt.options as { routeRules?: Record<string, Record<string, unknown>> }
+      const rules = (options.routeRules ??= {})
+      for (const path of paths) rules[path] = { cache: false, robots: 'noindex, follow', ...(rules[path] ?? {}) }
+      const opts = nuxt.options as { sitemap?: { exclude?: Array<string | RegExp> } }
+      opts.sitemap = { ...(opts.sitemap ?? {}), exclude: [...(opts.sitemap?.exclude ?? []), ...paths] }
+    }
+
     // Register the layer's strings only for locales the app enables. The
     // layer config declares no locales: @nuxtjs/i18n merges every locale a
     // layer declares into the app, which would add /en routes to an app that