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/java/com/cameleer3/server/app/Cameleer3ServerApplication.java

@@ -1,5 +1,6 @@
 package com.cameleer3.server.app;
 
+import com.cameleer3.server.app.config.AgentRegistryConfig;
 import com.cameleer3.server.app.config.IngestionConfig;
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
@@ -16,7 +17,7 @@ import org.springframework.scheduling.annotation.EnableScheduling;
         "com.cameleer3.server.core"
 })
 @EnableScheduling
-@EnableConfigurationProperties(IngestionConfig.class)
+@EnableConfigurationProperties({IngestionConfig.class, AgentRegistryConfig.class})
 public class Cameleer3ServerApplication {
 
     public static void main(String[] args) {