feat(analysis): scoped admin re-enqueue (all/manga/chapter) + force-on-include

Generalizes the admin re-enqueue beyond global backfill:

- repo::page_analysis::enqueue_pages(scope, only_unanalyzed) with
  ReenqueueScope::{All,Manga,Chapter}. Fixes include-analyzed semantics:
  only_unanalyzed=false now enqueues jobs with force=true so the worker
  actually re-analyzes already-done pages instead of skipping them.
- POST /v1/admin/analysis/reenqueue accepts optional manga_id / chapter_id
  (mutually exclusive, 404 on unknown target) alongside only_unanalyzed.

Tests: manga/chapter scope counts, include-analyzed sets force=true on the
done page, mutual-exclusivity 422, unknown-target 404. Existing global
backfill tests still green (13 total).

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

frontend/package.json

@@ -1,6 +1,6 @@
 {
   "name": "mangalord-frontend",
-  "version": "0.71.0",
+  "version": "0.72.0",
   "private": true,
   "type": "module",
   "scripts": {