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

pom.xml

@@ -30,22 +30,22 @@
   </dependencyManagement>
 
   <dependencies>
-    <!-- REST server (resteasy-reactive successor) -->
+    <!-- REST server (reactive) -->
     <dependency>
       <groupId>io.quarkus</groupId>
-      <artifactId>quarkus-resteasy</artifactId>
+      <artifactId>quarkus-rest</artifactId>
     </dependency>
 
     <!-- Qute templating -->
     <dependency>
       <groupId>io.quarkus</groupId>
-      <artifactId>quarkus-resteasy-qute</artifactId>
+      <artifactId>quarkus-rest-qute</artifactId>
     </dependency>
 
     <!-- REST Client -->
     <dependency>
       <groupId>io.quarkus</groupId>
-      <artifactId>quarkus-resteasy-client</artifactId>
+      <artifactId>quarkus-rest-client</artifactId>
     </dependency>
 
     <!-- CDI -->
@@ -75,7 +75,7 @@
     </dependency>
     <dependency>
       <groupId>io.quarkus</groupId>
-      <artifactId>quarkus-resteasy-client-jackson</artifactId>
+      <artifactId>quarkus-rest-client-jackson</artifactId>
     </dependency>
 
     <!-- Test -->