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

Cargo.toml

@@ -18,7 +18,7 @@ tonic = { version = "0.14", features = ["tls-ring"] }
 prost = "0.14"
 prost-types = "0.14"
 tonic-build = "0.14"
-tonic-health = "0.14"
+tonic-health = "0.14.6"
 tonic-prost = "0.14"
 tokio = { version = "1", features = ["full"] }
 actix-web = { version = "4", features = [] }
@@ -46,11 +46,12 @@ tracing-opentelemetry = "0.33"
 opentelemetry-appender-tracing = "0.32"
 opentelemetry-prometheus = "0.32"
 prometheus = "0.14"
-fred = { version = "10", features = ["subscriber-client"] }
+redis = { version = "1", features = ["cluster", "cluster-async", "aio", "tokio-comp", "connection-manager"] }
 async-nats = "0.38"
 futures-util = "0.3"
 jsonwebtoken = "9"
 arc-swap = "1"
+dotenvy = "0.15"
 
 
 [build-dependencies]