sync: add AI review pipeline, parallel skill-files fetch, Redis cache improvements

- feat(review): add skill_reviews table, review API endpoints (pending/submit/stats), admin auth
- perf: parallel file fetching in skill-files API (was sequential → timeout)
- fix: handle Date serialization from Redis cache
- fix: align curation batch scripts with current browseReadyFilter

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.gitignore

@@ -43,6 +43,10 @@ drizzle/*.sql
 *.dump
 data/backups/
 
+# Curation session data (review batches/results contain raw_content)
+scripts/curation/data/*
+!scripts/curation/data/.gitkeep
+
 # Claude Code
 .claude/skills/
 .claude/settings.local.json