feat: server-side GitHub search for issue/PR pickers (#1352)

Replace local-only filtering in GitHub issue/PR picker dialogs with
server-side GitHub Search API queries. Search text is sent as a query
parameter to the server, which uses the GitHub Search API
(issuesAndPullRequests endpoint) with repo: qualifiers including fork
network support. Results are debounced at 350ms to respect API rate
limits.

- Add query parameter to GitHubAPI issuesList/prsList interface
- Server routes use Search API when query is present, standard list
  endpoint when absent
- Fork networks handled via repo:owner/repo OR repo:owner/upstream
- PR search fetches full PR details after Search API for head/base/draft
  fields
- Remove local filter memos from all three picker dialogs
- Add debounced search effect with abort controller cleanup
- Update VS Code backend and webview API for parity
- Update search placeholders in all locales

Closes #1350

Co-authored-by: Bohdan Triapitsyn <artmore@protonmail.com>

packages/vscode/src/githubPulls.ts

@@ -285,12 +285,77 @@ export const listPullRequests = async (
   accessToken: string,
   directory: string,
   page: number = 1,
+  searchQuery?: string,
 ): Promise<GitHubPullRequestsListResult> => {
   const repo = await resolveRepoFromDirectory(directory);
   if (!repo) {
     return { connected: true, repo: null, prs: [] };
   }
 
+  if (searchQuery) {
+    const q = `repo:${repo.owner}/${repo.repo} ${searchQuery} type:pr state:open`;
+    const searchUrl = new URL(`${API_BASE}/search/issues`);
+    searchUrl.searchParams.set('q', q);
+    searchUrl.searchParams.set('per_page', '50');
+    searchUrl.searchParams.set('page', String(page));
+
+    const searchResp = await githubFetch(searchUrl.toString(), accessToken);
+    if (searchResp.status === 401) return { connected: false };
+
+    const searchJson = await jsonOrNull<{ total_count?: number; items?: unknown[] }>(searchResp);
+    if (!searchResp.ok || !searchJson) {
+      throw new Error('Failed to search PRs');
+    }
+
+    const totalCount = typeof searchJson.total_count === 'number' ? searchJson.total_count : 0;
+    const searchItems = Array.isArray(searchJson.items) ? searchJson.items : [];
+    const prNumbers = searchItems.map((item) => {
+      const rec = item && typeof item === 'object' ? (item as JsonRecord) : null;
+      return typeof rec?.number === 'number' ? rec.number : 0;
+    }).filter((n) => n > 0);
+
+    let prs: GitHubPullRequestSummary[] = [];
+    if (prNumbers.length > 0) {
+      const entries = await Promise.all(prNumbers.map(async (number) => {
+        const prUrl = new URL(`${API_BASE}/repos/${repo.owner}/${repo.repo}/pulls/${number}`);
+        const prResp = await githubFetch(prUrl.toString(), accessToken);
+        if (prResp.status === 401) return 'unauthorized' as const;
+        if (!prResp.ok) return null;
+        return jsonOrNull<JsonRecord>(prResp);
+      }));
+      if (entries.includes('unauthorized')) return { connected: false };
+      prs = entries
+        .filter((entry): entry is JsonRecord => Boolean(entry) && entry !== 'unauthorized')
+        .map((rec) => {
+          const number = typeof rec?.number === 'number' ? rec.number : 0;
+          const mergedAt = readString(rec?.merged_at);
+          const stateRaw = readString(rec?.state);
+          const state = mergedAt ? 'merged' : (stateRaw === 'closed' ? 'closed' : 'open');
+          const base = rec?.base && typeof rec.base === 'object' ? (rec.base as JsonRecord) : null;
+          const head = rec?.head && typeof rec.head === 'object' ? (rec.head as JsonRecord) : null;
+          return {
+            number,
+            title: readString(rec?.title) || '',
+            url: readString(rec?.html_url) || '',
+            state,
+            draft: Boolean(rec?.draft),
+            base: readString(base?.ref) || '',
+            head: readString(head?.ref) || '',
+            headSha: readString(head?.sha) || undefined,
+            mergeable: typeof rec?.mergeable === 'boolean' ? rec.mergeable : null,
+            mergeableState: readString(rec?.mergeable_state) || undefined,
+            author: mapUser(rec?.user),
+            headLabel: readString(head?.label) || undefined,
+            headRepo: mapHeadRepo(head?.repo),
+          } as GitHubPullRequestSummary;
+        });
+    }
+
+    const fetchedCount = (page - 1) * 50 + searchItems.length;
+    const hasMore = fetchedCount < totalCount;
+    return { connected: true, repo, prs, page, hasMore };
+  }
+
   const url = new URL(`${API_BASE}/repos/${repo.owner}/${repo.repo}/pulls`);
   url.searchParams.set('state', 'open');
   url.searchParams.set('per_page', '50');