Add Azure AKS deployment support with Key Vault integration and topology constraints

[Copilot]

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

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[cosmic-flood]

@copilot should i add v0.8.3 in the title?

[Copilot]

@copilot should i add v0.8.3 in the title?

The current chart version is 0.8.2. Since this PR adds new optional features (volumeMounts, topologySpreadConstraints, initContainer resources) and a new AKS example, it would be appropriate to bump to 0.8.3 following semantic versioning (minor/patch increment for backward-compatible additions).

However, whether to include the version in the PR title is a project convention preference. Common approaches:

• Include version: "v0.8.3: Add Azure AKS deployment support..." (useful for release tracking)
• Exclude version: Current title (cleaner, version bump happens during merge/release)

If you want the version in the title, you'd also need to update Chart.yaml version from 0.8.2 to 0.8.3 in this PR. If version bumps happen separately during release, keep the current title.