feat(server): add gitks gRPC server with environment configuration

- Add dotenvy dependency for environment variable loading
- Integrate tracing-subscriber for structured logging
- Create main.rs entry point with async server initialization
- Implement environment-based host and port configuration
- Set default address to 0.0.0:50051 for gRPC server
- Add proper error handling with Box<dyn std::error::Error>

Cargo.toml

@@ -28,6 +28,12 @@ prost = "0.13"
 prost-types = "0.13"
 tonic = { version = "0.12", features = ["transport"] }
 tempfile = "3"
+dotenvy = "0.15"
+tracing-subscriber = { version = "0.3", features = ["env-filter"] }
+
+[[bin]]
+name = "gitks"
+path = "main.rs"
 
 [build-dependencies]
 tonic-build = "0.12"