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/agent/AgentLifecycleMonitor.java

@@ -0,0 +1,36 @@
+package com.cameleer3.server.app.agent;
+
+import com.cameleer3.server.core.agent.AgentRegistryService;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.scheduling.annotation.Scheduled;
+import org.springframework.stereotype.Component;
+
+/**
+ * Periodic task that checks agent lifecycle and expires old commands.
+ * <p>
+ * Runs on a configurable fixed delay (default 10 seconds). Transitions
+ * agents LIVE -> STALE -> DEAD based on heartbeat timing, and removes
+ * expired pending commands.
+ */
+@Component
+public class AgentLifecycleMonitor {
+
+    private static final Logger log = LoggerFactory.getLogger(AgentLifecycleMonitor.class);
+
+    private final AgentRegistryService registryService;
+
+    public AgentLifecycleMonitor(AgentRegistryService registryService) {
+        this.registryService = registryService;
+    }
+
+    @Scheduled(fixedDelayString = "${agent-registry.lifecycle-check-interval-ms:10000}")
+    public void checkLifecycle() {
+        try {
+            registryService.checkLifecycle();
+            registryService.expireOldCommands();
+        } catch (Exception e) {
+            log.error("Error during agent lifecycle check", e);
+        }
+    }
+}