feat: Add Helm chart for Kubernetes deployment

[lowhung]

Summary

Package buswatch for Kubernetes deployment with Helm.

Proposed Features

• Deployment/StatefulSet options
• Service and Ingress configuration
• ConfigMap for settings
• Resource limits and requests
• Pod disruption budgets
• Horizontal pod autoscaling

Structure

charts/buswatch/
├── Chart.yaml
├── values.yaml
├── templates/
│   ├── deployment.yaml
│   ├── service.yaml
│   ├── configmap.yaml
│   └── ...

Benefits

• Standard Kubernetes deployment
• Easy configuration
• GitOps compatible