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/rbac/RbacServiceImpl.java

@@ -1,6 +1,12 @@
 package com.cameleer3.server.app.rbac;
 
-import com.cameleer3.server.core.rbac.*;
+import com.cameleer3.server.core.rbac.GroupRepository;
+import com.cameleer3.server.core.rbac.GroupSummary;
+import com.cameleer3.server.core.rbac.RbacService;
+import com.cameleer3.server.core.rbac.RbacStats;
+import com.cameleer3.server.core.rbac.RoleSummary;
+import com.cameleer3.server.core.rbac.UserDetail;
+import com.cameleer3.server.core.rbac.UserSummary;
 import com.cameleer3.server.core.security.UserInfo;
 import com.cameleer3.server.core.security.UserRepository;
 import org.springframework.jdbc.core.JdbcTemplate;
@@ -14,14 +20,12 @@ public class RbacServiceImpl implements RbacService {
     private final JdbcTemplate jdbc;
     private final UserRepository userRepository;
     private final GroupRepository groupRepository;
-    private final RoleRepository roleRepository;
 
     public RbacServiceImpl(JdbcTemplate jdbc, UserRepository userRepository,
-                           GroupRepository groupRepository, RoleRepository roleRepository) {
+                           GroupRepository groupRepository) {
         this.jdbc = jdbc;
         this.userRepository = userRepository;
         this.groupRepository = groupRepository;
-        this.roleRepository = roleRepository;
     }
 
     @Override