feat(admin): Crawler dashboard — live status, controls, dead-job requeue

New /admin/crawler tab (5s-polled): status hero (daemon/session/browser
pills, phase line + progress bar, session-expired banner, last-pass),
controls (run pass, restart browser w/ confirm, manage session modal,
clear expired), queue gauges + worker table, and a dead-jobs table with
search, Pager, and per-job / per-manga / all requeue.

Adds inline "requeue" on failed chapters in the admin manga page, the
typed api-client functions in lib/api/admin.ts (+ tests), and the Crawler
nav tab. Version 0.52.0 -> 0.53.0.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/lib/api/admin.ts

@@ -214,3 +214,105 @@ export async function resyncChapter(id: string): Promise<ChapterResyncResponse>
         { method: 'POST' }
     );
 }
+
+// ---- crawler observability + control ---------------------------------------
+
+/** Current daemon activity. Discriminated on `state`. */
+export type CrawlerPhase =
+    | { state: 'idle'; next_fire: string | null }
+    | { state: 'walking_list' }
+    | { state: 'fetching_metadata'; index: number; total: number | null; title: string }
+    | { state: 'cover_backfill' };
+
+export type CrawlerWorker = { state: 'idle' } | { state: 'working'; chapter_id: string };
+
+export type CrawlerLastPass = {
+    at: string | null;
+    discovered: number;
+    upserted: number;
+    covers_fetched: number;
+    mangas_failed: number;
+};
+
+export type CrawlerStatus = {
+    daemon: 'running' | 'disabled';
+    phase: CrawlerPhase | null;
+    workers: CrawlerWorker[];
+    last_pass: CrawlerLastPass;
+    session: { expired: boolean; configured: boolean };
+    browser: 'healthy' | 'draining' | 'restarting' | 'down';
+    queue: { pending: number; running: number; dead: number };
+};
+
+export async function getCrawlerStatus(): Promise<CrawlerStatus> {
+    return request<CrawlerStatus>('/v1/admin/crawler');
+}
+
+/** POST /v1/admin/crawler/run — trigger an out-of-cycle metadata pass. */
+export async function runCrawlerPass(): Promise<{ started: boolean }> {
+    return request('/v1/admin/crawler/run', { method: 'POST' });
+}
+
+/** POST /v1/admin/crawler/browser/restart — coordinated Chromium restart. */
+export async function restartCrawlerBrowser(): Promise<{ ok: boolean; error: string | null }> {
+    return request('/v1/admin/crawler/browser/restart', { method: 'POST' });
+}
+
+/** POST /v1/admin/crawler/session — refresh PHPSESSID and re-probe. */
+export async function updateCrawlerSession(
+    phpsessid: string
+): Promise<{ valid: boolean; error: string | null }> {
+    return request('/v1/admin/crawler/session', {
+        method: 'POST',
+        headers: { 'content-type': 'application/json' },
+        body: JSON.stringify({ phpsessid })
+    });
+}
+
+/** POST /v1/admin/crawler/session/clear-expired — resume idled workers. */
+export async function clearCrawlerSessionExpired(): Promise<{ cleared: boolean }> {
+    return request('/v1/admin/crawler/session/clear-expired', { method: 'POST' });
+}
+
+export type DeadJob = {
+    id: string;
+    kind: string;
+    chapter_id: string | null;
+    manga_id: string | null;
+    manga_title: string | null;
+    chapter_number: number | null;
+    attempts: number;
+    max_attempts: number;
+    last_error: string | null;
+    updated_at: string;
+};
+
+export type DeadJobsPage = { items: DeadJob[]; page: Page };
+
+export async function listDeadJobs(opts?: {
+    search?: string;
+    limit?: number;
+    offset?: number;
+}): Promise<DeadJobsPage> {
+    const params = new URLSearchParams();
+    if (opts?.search) params.set('search', opts.search);
+    if (opts?.limit != null) params.set('limit', String(opts.limit));
+    if (opts?.offset != null) params.set('offset', String(opts.offset));
+    const qs = params.toString();
+    return request<DeadJobsPage>(`/v1/admin/crawler/dead-jobs${qs ? `?${qs}` : ''}`);
+}
+
+/** Requeue scope: all dead jobs, one manga's, one chapter's, or a single job. */
+export type RequeueScope =
+    | { scope: 'all' }
+    | { scope: 'manga'; manga_id: string }
+    | { scope: 'chapter'; chapter_id: string }
+    | { scope: 'job'; job_id: string };
+
+export async function requeueDeadJobs(scope: RequeueScope): Promise<{ requeued: number }> {
+    return request('/v1/admin/crawler/dead-jobs/requeue', {
+        method: 'POST',
+        headers: { 'content-type': 'application/json' },
+        body: JSON.stringify(scope)
+    });
+}