feat(search): tag-based page search surface + per-page tags & collections

Add the /search surface (Pages / Chapters / Mangas tabs) backed by
per-user page tags and per-page collections: schema (migration 0023),
backend endpoints for page tags/collections and tagged-page aggregations
(with the OCR text-search param reserved at 501), plus the frontend API
clients, library Page-tags tab, collection page sections, page context
menu / AddTagsSheet, and reader long-press wiring. Includes the
continuous-reader navigation fixes (?page=N handling, chapter-reset
timing, back-button pops history) and tag-normalization hardening
accumulated on the branch.

Bump version 0.60.2 -> 0.62.0.

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

frontend/src/lib/components/AddToCollectionModal.svelte.test.ts

@@ -0,0 +1,100 @@
+import { describe, it, expect, vi, afterEach } from 'vitest';
+import { render, screen, cleanup } from '@testing-library/svelte';
+import { tick } from 'svelte';
+import AddToCollectionModal from './AddToCollectionModal.svelte';
+
+// Stub the API modules at the import-graph level so the modal exercises
+// its dispatch (manga vs page) without hitting fetch.
+const collectionsApi = vi.hoisted(() => ({
+    listMyCollections: vi.fn(),
+    getMyCollectionsContaining: vi.fn(),
+    addMangaToCollection: vi.fn(),
+    removeMangaFromCollection: vi.fn(),
+    createCollection: vi.fn()
+}));
+const pageCollectionsApi = vi.hoisted(() => ({
+    getMyCollectionsContainingPage: vi.fn(),
+    addPageToCollection: vi.fn(),
+    removePageFromCollection: vi.fn()
+}));
+
+vi.mock('$lib/api/collections', () => collectionsApi);
+vi.mock('$lib/api/page_collections', () => pageCollectionsApi);
+
+afterEach(() => {
+    cleanup();
+    vi.clearAllMocks();
+});
+
+function summary(id: string, name: string, containing: string[] = []) {
+    return {
+        id,
+        user_id: 'u1',
+        name,
+        description: null,
+        created_at: '2026-01-01T00:00:00Z',
+        updated_at: '2026-01-01T00:00:00Z',
+        manga_count: 0,
+        sample_covers: [],
+        _containing: containing
+    };
+}
+
+describe('AddToCollectionModal', () => {
+    it('manga target loads via getMyCollectionsContaining', async () => {
+        collectionsApi.listMyCollections.mockResolvedValueOnce({
+            items: [summary('c1', 'Favorites')],
+            page: { limit: 200, offset: 0, total: 1 }
+        });
+        collectionsApi.getMyCollectionsContaining.mockResolvedValueOnce(['c1']);
+
+        render(AddToCollectionModal, {
+            props: {
+                open: true,
+                target: { kind: 'manga', id: 'm1' },
+                onClose: () => {}
+            }
+        });
+        // Wait for the $effect → load() → await chain to settle.
+        await tick();
+        await Promise.resolve();
+        await tick();
+
+        expect(collectionsApi.getMyCollectionsContaining).toHaveBeenCalledWith('m1');
+        expect(pageCollectionsApi.getMyCollectionsContainingPage).not.toHaveBeenCalled();
+    });
+
+    it('page target loads via getMyCollectionsContainingPage', async () => {
+        collectionsApi.listMyCollections.mockResolvedValueOnce({
+            items: [summary('c1', 'Favorite panels')],
+            page: { limit: 200, offset: 0, total: 1 }
+        });
+        pageCollectionsApi.getMyCollectionsContainingPage.mockResolvedValueOnce([]);
+
+        render(AddToCollectionModal, {
+            props: {
+                open: true,
+                target: { kind: 'page', id: 'p1' },
+                onClose: () => {}
+            }
+        });
+        await tick();
+        await Promise.resolve();
+        await tick();
+
+        expect(pageCollectionsApi.getMyCollectionsContainingPage).toHaveBeenCalledWith('p1');
+        expect(collectionsApi.getMyCollectionsContaining).not.toHaveBeenCalled();
+        expect(screen.getByText('Favorite panels')).toBeTruthy();
+    });
+
+    it('does not load when closed', () => {
+        render(AddToCollectionModal, {
+            props: {
+                open: false,
+                target: { kind: 'manga', id: 'm1' },
+                onClose: () => {}
+            }
+        });
+        expect(collectionsApi.listMyCollections).not.toHaveBeenCalled();
+    });
+});