feat(registry): add service discovery and health check capabilities

- Integrate tonic-health for gRPC service health monitoring
- Add etcd-based service registration with automatic keep-alive
- Implement dynamic configuration loading from etcd with fallback
- Remove external dependencies from docker-compose for simplified deployment
- Refactor service registration logic with improved lease management
- Add health service to gRPC server with serving status reporting

main.rs

@@ -39,11 +39,9 @@ async fn main() -> AppResult<()> {
 
     let registry = Arc::new(EtcdRegistry::connect(&config).await?);
     registry.start_discovery().await?;
-    if config.get_env_or("APP_ETCD_REGISTER_SELF", false)? {
-        registry
-            .register_self(&config.rpc_self_service_name()?)
-            .await?;
-    }
+    registry
+        .register_self(&config.rpc_self_service_name()?)
+        .await?;
 
     let nats = Arc::new(NatsQueue::connect(&config).await?);