feat(config): integrate etcd for service discovery and config management

- Add etcd-client dependency for distributed configuration storage
- Implement EtcdConfig with priority: etcd > environment variables > defaults
- Add ServiceRegistry for service registration with lease keep-alive
- Integrate etcd-based service discovery for appks gRPC connections
- Add service watcher for real-time service instance updates
- Migrate Redis configuration from single URL to cluster node list
- Update Dockerfile with default IMKS_HOST and IMKS_PORT environment variables
- Add etcd bootstrap configuration through environment variables
- Implement Redis cluster URL building with optional authentication

telemetry/health.rs

@@ -52,10 +52,7 @@ pub fn connections_active_count() -> u64 {
 
 /// Returns the server uptime in seconds.
 pub fn uptime_secs() -> u64 {
-    START_TIME
-        .get()
-        .map(|t| t.elapsed().as_secs())
-        .unwrap_or(0)
+    START_TIME.get().map(|t| t.elapsed().as_secs()).unwrap_or(0)
 }
 
 #[derive(Debug, Clone, Serialize)]
@@ -147,11 +144,7 @@ pub async fn health_check(checks: actix_web::web::Data<Arc<HealthCheckFns>>) ->
             .iter()
             .filter_map(|c| c.as_ref())
             .all(|c| c.status == "up");
-        if all_up {
-            "healthy"
-        } else {
-            "degraded"
-        }
+        if all_up { "healthy" } else { "degraded" }
     } else {
         "healthy"
     };