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>

public/discover.js

@@ -49,7 +49,7 @@
     const refreshState = state.refresh || { state: 'idle' };
     const label = refreshState.state === 'queued' ? `Queued (position ${refreshState.position})`
       : refreshState.state === 'running' ? 'Fetching…'
-        : refreshState.blockedReason ? `Paused by AniList (${refreshState.blockedReason}) until the next nightly run`
+        : refreshState.blockedReason ? `Paused by AniList (${refreshState.blockedReason}) until the next nightly or admin harvest`
           : refreshState.nextAllowedAt ? `Next refresh possible at ${clock(refreshState.nextAllowedAt)}` : null;
     return h('button', { type: 'button', class: 'btn discovery-refresh', disabled: !!label, onclick: refreshMine }, label || 'Refresh my suggestions');
   }
@@ -60,7 +60,7 @@
   }
   function preferences() {
     return h('section', { class: 'card discovery-settings' }, h('h2', {}, 'Your discovery preferences'),
-      toggle('Personalized discovery', 'discoveryEnabled', 'Off by default. When on, the server sends AniList the IDs of titles you liked, without login, to find related work. Your feed and feedback stay private to this server.'),
+      toggle('Personalized discovery', 'discoveryEnabled', 'Off by default. When on, the server sends AniList the IDs of titles you liked, read or own, their authors\' IDs and your top tags, without login, to find related work. Your feed and feedback stay private to this server.'),
       toggle('Use reading activity', 'discoveryReadingActivity', 'Separately opt in to using completed chapters as a small taste signal.'),
       toggle('Include mature titles', 'discoveryMature', 'Only affects titles AniList marks as adult or with a known mature tag.'));
   }