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/e2e/page-context-menu.spec.ts

@@ -73,7 +73,12 @@ const collectionFixture = {
  */
 async function mockReader(
     page: Page,
-    state: { collectionsContainingPage: string[]; tagsOnPage: string[] }
+    state: {
+        collectionsContainingPage: string[];
+        tagsOnPage: string[];
+        admin?: boolean;
+        analyzeCalls?: number;
+    }
 ) {
     await page.route('**/api/v1/auth/config', (route) =>
         route.fulfill({
@@ -86,9 +91,20 @@ async function mockReader(
         route.fulfill({
             status: 200,
             contentType: 'application/json',
-            body: JSON.stringify({ user: userFixture })
+            body: JSON.stringify({
+                user: { ...userFixture, is_admin: state.admin ?? false }
+            })
         })
     );
+    // Admin force-analyze endpoint — counts invocations for assertions.
+    await page.route(`**/api/v1/admin/pages/${pageId}/analyze`, (route) => {
+        state.analyzeCalls = (state.analyzeCalls ?? 0) + 1;
+        return route.fulfill({
+            status: 200,
+            contentType: 'application/json',
+            body: JSON.stringify({ enqueued: true })
+        });
+    });
     await page.route('**/api/v1/auth/me/preferences', (route) =>
         route.fulfill({
             status: 200,
@@ -266,6 +282,37 @@ test.describe('page context menu (desktop right-click)', () => {
         );
     });
 
+    test('non-admin does not see the Queue for analysis action', async ({ page }) => {
+        await mockReader(page, { collectionsContainingPage: [], tagsOnPage: [] });
+        await page.setViewportSize(DESKTOP);
+        await page.goto(`/manga/${mangaId}/chapter/${chapterId}`);
+
+        await page.getByTestId('reader-page').click({ button: 'right' });
+        await expect(page.getByTestId('page-context-menu')).toBeVisible();
+        await expect(page.getByTestId('page-context-analyze')).toBeHidden();
+    });
+
+    test('admin can queue the page for analysis from the menu', async ({ page }) => {
+        const state = {
+            collectionsContainingPage: [],
+            tagsOnPage: [],
+            admin: true,
+            analyzeCalls: 0
+        };
+        await mockReader(page, state);
+        await page.setViewportSize(DESKTOP);
+        await page.goto(`/manga/${mangaId}/chapter/${chapterId}`);
+
+        await page.getByTestId('reader-page').click({ button: 'right' });
+        const item = page.getByTestId('page-context-analyze');
+        await expect(item).toBeVisible();
+        await expect(item).toContainText('Queue for analysis');
+
+        await item.click();
+        await expect(item).toContainText('Queued for analysis');
+        expect(state.analyzeCalls).toBe(1);
+    });
+
     test('Shift+right-click falls through to the browser native menu', async ({
         page
     }) => {