feat(analysis): admin UI — reader context-menu action + dashboard section

Surfaces the scoped re-enqueue and per-page force-analyze in the UI:

- api/admin: reenqueueAnalysis({onlyUnanalyzed, mangaId, chapterId}) and
  analyzePage(pageId).
- Reader PageContextMenu gains an admin-only "Queue for analysis" item
  (canAnalyze/onAnalyzePage/analyzeState props) wired to the force-analyze
  endpoint with inline busy/done/error feedback; reset per page.
- New /admin/analysis dashboard section + nav tab: scope selector
  (whole library / one manga / one chapter), id input, and an
  "include already-analyzed" toggle (default off), with busy/notice/error.

Tests: vitest for the two clients; Playwright for the context-menu action
(admin vs non-admin) and the admin section (scope + include toggle +
validation). svelte-check + build clean; 262 vitest, 10 new e2e green.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/src/lib/api/admin.test.ts

@@ -26,7 +26,9 @@ import {
     listDeadJobs,
     requeueDeadJobs,
     listActiveJobs,
-    listMissingCovers
+    listMissingCovers,
+    reenqueueAnalysis,
+    analyzePage
 } from './admin';
 
 function ok(body: unknown, status = 200): Response {
@@ -494,4 +496,42 @@ describe('admin crawler api client', () => {
         fetchSpy.mockResolvedValueOnce(envelope(503, 'service_unavailable', 'disabled'));
         await expect(runCrawlerPass()).rejects.toMatchObject({ status: 503 });
     });
+
+    it('reenqueueAnalysis defaults to whole-library, exclude-analyzed', async () => {
+        fetchSpy.mockResolvedValueOnce(ok({ enqueued: 42 }));
+        const r = await reenqueueAnalysis();
+        expect(r.enqueued).toBe(42);
+        const url = fetchSpy.mock.calls[0][0] as string;
+        expect(url).toMatch(/\/v1\/admin\/analysis\/reenqueue$/);
+        expect(JSON.parse(fetchSpy.mock.calls[0][1]!.body as string)).toEqual({
+            only_unanalyzed: true
+        });
+    });
+
+    it('reenqueueAnalysis scopes to a manga and can include analyzed', async () => {
+        fetchSpy.mockResolvedValueOnce(ok({ enqueued: 7 }));
+        await reenqueueAnalysis({ mangaId: 'm1', onlyUnanalyzed: false });
+        expect(JSON.parse(fetchSpy.mock.calls[0][1]!.body as string)).toEqual({
+            only_unanalyzed: false,
+            manga_id: 'm1'
+        });
+    });
+
+    it('reenqueueAnalysis scopes to a chapter', async () => {
+        fetchSpy.mockResolvedValueOnce(ok({ enqueued: 3 }));
+        await reenqueueAnalysis({ chapterId: 'c1' });
+        expect(JSON.parse(fetchSpy.mock.calls[0][1]!.body as string)).toEqual({
+            only_unanalyzed: true,
+            chapter_id: 'c1'
+        });
+    });
+
+    it('analyzePage posts to the force-analyze endpoint', async () => {
+        fetchSpy.mockResolvedValueOnce(ok({ enqueued: true }));
+        const r = await analyzePage('p1');
+        expect(r.enqueued).toBe(true);
+        const url = fetchSpy.mock.calls[0][0] as string;
+        expect(url).toMatch(/\/v1\/admin\/pages\/p1\/analyze$/);
+        expect(fetchSpy.mock.calls[0][1]!.method).toBe('POST');
+    });
 });