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/routes/search/+page.ts

@@ -0,0 +1,92 @@
+import { ApiError } from '$lib/api/client';
+import {
+    listMyDistinctPageTags,
+    listMyPageTags,
+    listTaggedChapters,
+    listTaggedMangas,
+    type PageTagSummary,
+    type TaggedChapterAggregate,
+    type TaggedMangaAggregate,
+    type TaggedPageItem
+} from '$lib/api/page_tags';
+import type { PageLoad } from './$types';
+
+export const ssr = false;
+
+type View = 'pages' | 'chapters' | 'mangas';
+type Order = 'desc' | 'asc';
+
+/**
+ * Loader for the /search page. URL is the source of truth — refresh
+ * or share a link lands the user on the same view.
+ *
+ * - `?tag=` exact-match tag filter. Empty → no results, just the
+ *   chip cloud for browsing.
+ * - `?view=pages|chapters|mangas` — defaults to `pages` when omitted.
+ * - `?order=desc|asc` — only meaningful for chapters/mangas tabs.
+ *   `desc` (most matches first) is the default.
+ *
+ * `?text=` is reserved for the planned OCR text-search input. The
+ * backend rejects it with 501 + stable code
+ * `text_search_not_yet_supported` today; the frontend never sets it.
+ */
+export const load: PageLoad = async ({ url }) => {
+    const tag = url.searchParams.get('tag');
+    const viewParam = url.searchParams.get('view');
+    const view: View =
+        viewParam === 'chapters' || viewParam === 'mangas' ? viewParam : 'pages';
+    const order: Order = url.searchParams.get('order') === 'asc' ? 'asc' : 'desc';
+
+    const empty = {
+        authenticated: true,
+        tag,
+        view,
+        order,
+        distinct: [] as PageTagSummary[],
+        pages: [] as TaggedPageItem[],
+        chapters: [] as TaggedChapterAggregate[],
+        mangas: [] as TaggedMangaAggregate[],
+        total: 0,
+        error: null as string | null
+    };
+
+    try {
+        const distinct = await listMyDistinctPageTags(undefined, 100);
+        // No tag selected → just the chip cloud.
+        if (!tag) return { ...empty, distinct };
+
+        if (view === 'chapters') {
+            const r = await listTaggedChapters({ tag, order, limit: 100 });
+            return {
+                ...empty,
+                distinct,
+                chapters: r.items,
+                total: r.page.total ?? 0
+            };
+        }
+        if (view === 'mangas') {
+            const r = await listTaggedMangas({ tag, order, limit: 100 });
+            return {
+                ...empty,
+                distinct,
+                mangas: r.items,
+                total: r.page.total ?? 0
+            };
+        }
+        const r = await listMyPageTags({ tag, limit: 100 });
+        return {
+            ...empty,
+            distinct,
+            pages: r.items,
+            total: r.page.total ?? 0
+        };
+    } catch (e) {
+        if (e instanceof ApiError && e.status === 401) {
+            return { ...empty, authenticated: false };
+        }
+        if (e instanceof ApiError) {
+            return { ...empty, error: e.message };
+        }
+        throw e;
+    }
+};