Address all code review issues

- XSS: use hx-confirm instead of onclick confirm()
- Feed: per-artist type filtering in SQL with LIMIT/OFFSET
- Cache: batch staleness check (single query)
- Monitoring: null-guard + constant-first equals
- REST stack: switch to reactive (quarkus-rest)
- User-Agent: fix double https, update version
- Settings: validate cache TTL before saving
- Delete: transactional cascade
- Docker: remove unused sqlite package
- Explicit columns in findAllArtists

src/main/resources/application.properties

@@ -17,4 +17,4 @@ discdrop.cache.ttl-hours=${DISC_DROP_CACHE_TTL:8}
 discdrop.base-url=${DISC_DROP_BASE_URL:http://localhost:8080}
 
 # User-Agent sent to MusicBrainz API (env: DISC_DROP_USER_AGENT)
-discdrop.user-agent=${DISC_DROP_USER_AGENT:DiscDrop/0.1 (https://https://github.com/droideparanoico/discdrop)}
+discdrop.user-agent=${DISC_DROP_USER_AGENT:DiscDrop/1.0 (https://github.com/droideparanoico/discdrop)}