Discovery final review fixes: lean publish, robust scoring, cheap prune (BL-0051)

- Cache prune counts directory entries first and only reads files when over
  the cap; tests for cross-kind prune, schema-mismatch and corrupt entries.
- Scoring tolerates malformed manga.json and cached records (non-list tags,
  object or null relations, non-object items); a tag without a rank no longer
  passes the top-tag filter; authors without an integer AniList id are dropped.
- discovery.json publishes only candidates some feed shows; examined/clipped
  still describe the pool. Tests that asserted the published count equals the
  pool size now check the pool via candidatePool() and the published set
  against the feeds.
- The post-harvest rescore failure test now breaks discovery.json right before
  the publish (via a scraper stand-in) instead of relying on tags: 5, and a
  following successful harvest clears the stale lastError.
- Consent text names everything sent to AniList; paused label mentions admin
  harvests; the UI test asserts the XSS seed instead of skipping it.
- Slot-mix test proves the fresh/outside reservations matter.
- Docs: privacy note, fresh fallback reason, per-period cap, dry-run wording,
  published-candidate rule; plan/spec hygiene and spec status.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

test/discovery-anchors.test.js

@@ -60,3 +60,14 @@ test('top tags weigh anchors, skip low rank and adult tags', () => {
   assert.deepEqual(topTagsFor(anchors, recordOf, { mature: true }), [
     { name: 'Action', kind: 'genre' }, { name: 'Ecchi', kind: 'tag' }, { name: 'Alpha', kind: 'tag' }]);
 });
+
+test('top tags drop tags without a rank and survive malformed records', () => {
+  const records = {
+    1: { tags: [{ name: 'NoRank', kind: 'tag', isAdult: false }, { name: 'NullRank', rank: null, kind: 'tag', isAdult: false },
+      null, 7, { name: 'Kept', rank: 60, kind: 'tag', isAdult: false }] },
+    2: { tags: 5 },
+    3: { tags: { name: 'Object', rank: 90 } },
+  };
+  const anchors = [{ anilistId: 1, weight: 5 }, { anilistId: 2, weight: 3 }, { anilistId: 3, weight: 3 }];
+  assert.deepEqual(topTagsFor(anchors, id => records[id]), [{ name: 'Kept', kind: 'tag' }]);
+});