v0.8.3: Add Azure AKS deployment support with Key Vault integration and topology constraints

[cosmic-flood]

Extends Helm chart compatibility with Azure Kubernetes Service (AKS Standard and AKS Automatic) through optional template enhancements and production-ready deployment example.

Template Enhancements

Added optional fields to all service deployments (API, UI, ELS, DAS):

• volumeMounts / volumes - Azure Key Vault CSI Driver integration for secret management
• topologySpreadConstraints - Pod distribution across nodes/zones for AKS Automatic policy compliance
• initContainers.resources - Resource limits/requests for init containers (AKS Automatic requirement)

All fields use {{- with }} conditionals for backward compatibility - existing deployments unaffected.

# Example: Azure Key Vault volume mount
api:
  volumeMounts:
    - name: secrets-store
      mountPath: "/mnt/secrets-store"
      readOnly: true
  volumes:
    - name: secrets-store
      csi:
        driver: secrets-store.csi.k8s.io
        volumeAttributes:
          secretProviderClass: "featbit-keyvault-secrets"

AKS Deployment Example

New charts/featbit/examples/aks/ with production architecture:

Internet → Traffic Manager → Azure LB → NGINX Ingress (TLS) → FeatBit

• featbit-aks-values.yaml - External PostgreSQL/Redis, Key Vault secrets, autoscaling config
• keyvault-secret-provider.yaml - SecretProviderClass for CSI Driver
• cluster-issuer.yaml - Let's Encrypt staging/production issuers
• README.md - Complete deployment guide: NGINX Ingress setup, cert-manager, Traffic Manager multi-region, troubleshooting

Configuration highlights:

• External PostgreSQL/Redis with Key Vault-managed credentials
• HPA targeting 80% CPU/memory with 3-10 replicas
• WebSocket-optimized NGINX timeouts (3600s)
• Pod security contexts for RuntimeDefault seccomp profile

Additional Changes

• .gitignore - Added *.local.yaml pattern for local config files

[cosmic-flood]

@copilot please help me to summarize what has been changed, and tell me the potential risks.

here's what I did:

• volumeMounts and .volumes changes, this is for store secret synced from azure keyvault service. those are optional

• topologySpreadConstraints, this for fit the restriction of azure kuberntes service automatic azure policy rules. optional

• .initContainers.resources, this for fit the restriction of azure kuberntes service automatic azure policy rules. optional

• examples/aks is the example to deploy featbit into aks with nginx, azure load balancer and traffic manger.

please also give me this pull request a title and description of the pull request by changes.

basically, all changes are for deploy this helm chart to aks standard (also aks automatic) + azure solution

[Copilot]

@cosmic-flood I've opened a new pull request, #61, to work on those changes. Once the pull request is ready, I'll request review from you.