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/api/mod.rs

@@ -9,6 +9,7 @@ pub mod genres;
 pub mod health;
 pub mod history;
 pub mod mangas;
+pub mod page_tags;
 pub mod pagination;
 pub mod tags;
 
@@ -28,6 +29,7 @@ pub fn routes() -> Router<AppState> {
         .merge(tags::routes())
         .merge(authors::routes())
         .merge(collections::routes())
+        .merge(page_tags::routes())
         .merge(history::routes())
         .merge(admin::routes())
 }