feat(k8s): add Kubernetes Helm chart for emailks service

- Create Helm chart structure with Chart.yaml and values.yaml
- Add deployment template with container configuration and environment variables
- Implement service template for gRPC port exposure
- Add service account template with security configuration
- Include horizontal pod autoscaler template for scaling capabilities
- Add helper templates for naming and label management
- Configure SMTP settings as configurable parameters in values.yaml
- Set up resource limits and requests for container performance
- Implement liveness and readiness probes for health checks
- Add support for existing secrets and custom configurations

Dockerfile

@@ -15,7 +15,7 @@ COPY build.rs ./
 COPY proto/ proto/
 RUN echo '' >lib.rs && \
     echo 'fn main() {}' >main.rs && \
-    cargo build --release; \
+    cargo build --release --bin emailks; \
     rm -f lib.rs main.rs
 
 # Build real binary