fix: resolve 25 SonarQube code smells across 21 files

Remove unused fields (log, rbacService, roleRepository, jwt),
unused variables (agentTps, routeKeys, updated), unused imports
(HttpHeaders, JdbcTemplate). Rename restricted identifier 'record'
to 'auditRecord'/'event'. Return empty collections instead of null.
Replace .collect(Collectors.toList()) with .toList(). Simplify
conditional return in BootstrapTokenValidator.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cameleer3-server-app/src/main/java/com/cameleer3/server/app/dto/AgentEventResponse.java

@@ -15,10 +15,10 @@ public record AgentEventResponse(
         String detail,
         @NotNull Instant timestamp
 ) {
-    public static AgentEventResponse from(AgentEventRecord record) {
+    public static AgentEventResponse from(AgentEventRecord event) {
         return new AgentEventResponse(
-                record.id(), record.instanceId(), record.applicationId(),
-                record.eventType(), record.detail(), record.timestamp()
+                event.id(), event.instanceId(), event.applicationId(),
+                event.eventType(), event.detail(), event.timestamp()
         );
     }
 }