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>

backend/src/domain/collection.rs

@@ -33,6 +33,22 @@ pub struct CollectionSummary {
     pub sample_covers: Vec<String>,
 }
 
+/// Row returned by `GET /collections/:id/pages`. Joins through
+/// `chapters` and `mangas` so the collection detail view can render a
+/// thumbnail + breadcrumb without per-row follow-up fetches.
+#[derive(Debug, Clone, Serialize, FromRow)]
+pub struct CollectionPageItem {
+    pub page_id: Uuid,
+    pub chapter_id: Uuid,
+    pub manga_id: Uuid,
+    pub page_number: i32,
+    pub chapter_number: i32,
+    pub chapter_title: Option<String>,
+    pub manga_title: String,
+    pub storage_key: String,
+    pub added_at: DateTime<Utc>,
+}
+
 #[derive(Debug, Clone, Deserialize)]
 pub struct NewCollection {
     pub name: String,