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>

server.js

@@ -317,8 +317,10 @@ try {
 const harvester = new Harvester({ cache: harvestCache, client: createAniListClient(), store: discoveryStore,
   targetsFor: harvestTargets, onDone: async job => {
     // A failed follow-up rescore must reach the admin panel (lastError), not only the log.
-    try { await rescore(job.kind === 'user' ? { onlyUser: job.user } : {}); }
-    catch (error) { discoveryError = `Re-scoring after harvest ${job.id} failed: ${String(error.message || error)}`.slice(0, 300); throw error; }
+    try {
+      await rescore(job.kind === 'user' ? { onlyUser: job.user } : {});
+      discoveryError = null; // a later success must not leave an old failure on the admin panel
+    } catch (error) { discoveryError = `Re-scoring after harvest ${job.id} failed: ${String(error.message || error)}`.slice(0, 300); throw error; }
   } });
 function requestHarvest(args) {
   readDiscovery(); // A corrupt store fails closed before any AniList call.