feat(03-01): add agent registration controller, config, lifecycle monitor

- AgentRegistryConfig: heartbeat, stale, dead, ping, command expiry settings
- AgentRegistryBeanConfig: wires AgentRegistryService as Spring bean
- AgentLifecycleMonitor: @Scheduled lifecycle check + command expiry sweep
- AgentRegistrationController: POST /register, POST /{id}/heartbeat, GET /agents
- Updated Cameleer3ServerApplication with AgentRegistryConfig
- Updated application.yml with agent-registry section and async timeout
- 7 integration tests: register, re-register, heartbeat, list, filter, invalid status

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

cameleer3-server-app/src/main/resources/application.yml

@@ -7,12 +7,23 @@ spring:
     username: cameleer
     password: cameleer_dev
     driver-class-name: com.clickhouse.jdbc.ClickHouseDriver
+  mvc:
+    async:
+      request-timeout: -1
   jackson:
     serialization:
       write-dates-as-timestamps: false
     deserialization:
       fail-on-unknown-properties: false
 
+agent-registry:
+  heartbeat-interval-ms: 30000
+  stale-threshold-ms: 90000
+  dead-threshold-ms: 300000
+  ping-interval-ms: 15000
+  command-expiry-ms: 60000
+  lifecycle-check-interval-ms: 10000
+
 ingestion:
   buffer-capacity: 50000
   batch-size: 5000