fix: agent token refresh returns 404 after server restart

The refresh endpoint required the agent to exist in the in-memory
registry. After server restart the registry is empty, so all refresh
attempts got 404. The refresh token itself is self-contained with
subject, application, and roles — the registry lookup is optional.

Now uses application from the JWT, falling back to registry only
if the agent happens to be registered.

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

cameleer3-server-app/src/main/java/com/cameleer3/server/app/controller/AgentRegistrationController.java

@@ -173,17 +173,19 @@ public class AgentRegistrationController {
             return ResponseEntity.status(401).build();
         }
 
-        // Verify agent exists
-        AgentInfo agent = registryService.findById(agentId);
-        if (agent == null) {
-            return ResponseEntity.notFound().build();
-        }
-
-        // Preserve roles from refresh token
+        // Preserve roles and application from refresh token
         List<String> roles = result.roles().isEmpty()
                 ? List.of("AGENT") : result.roles();
-        String newAccessToken = jwtService.createAccessToken(agentId, agent.applicationId(), roles);
-        String newRefreshToken = jwtService.createRefreshToken(agentId, agent.applicationId(), roles);
+        String application = result.application() != null ? result.application() : "default";
+
+        // Try to get application from registry if available (agent may not be registered after server restart)
+        AgentInfo agent = registryService.findById(agentId);
+        if (agent != null) {
+            application = agent.applicationId();
+        }
+
+        String newAccessToken = jwtService.createAccessToken(agentId, application, roles);
+        String newRefreshToken = jwtService.createRefreshToken(agentId, application, roles);
 
         auditService.log(agentId, "agent_token_refresh", AuditCategory.AUTH, agentId,
                 null, AuditResult.SUCCESS, httpRequest);