feat: Add lifecycle hooks, terminationGracePeriodSeconds

[aharonh]

Summary

Adds support for container lifecycle hooks and pod terminationGracePeriodSeconds to all 4 application deployment templates: API, TaskProcessor, Frontend, and SSE.

Currently the PgBouncer deployment template has a hardcoded preStop lifecycle hook, but none of the application deployments support configuring lifecycle hooks or termination grace periods via values.

Closes #507

Changes

• templates/deployment-api.yaml: Add lifecycle and terminationGracePeriodSeconds
• templates/deployment-task-processor.yaml: Add lifecycle and terminationGracePeriodSeconds
• templates/deployment-frontend.yaml: Add lifecycle and terminationGracePeriodSeconds
• templates/deployment-sse.yaml: Add lifecycle and terminationGracePeriodSeconds
• values.yaml: Add default values (lifecycle: {}, terminationGracePeriodSeconds: null) for all 4 components

Usage Example

api:
  terminationGracePeriodSeconds: 30
  lifecycle:
    preStop:
      exec:
        command: ["/bin/sh", "-c", "sleep 10"]

Backward Compatibility

• Defaults are lifecycle: {} and terminationGracePeriodSeconds: null, which means no change to existing deployments
• Both fields are rendered conditionally ({{- with }} / {{- if }}) so they are omitted entirely when not set

Testing

Verified with helm template that:

• All 4 templates render lifecycle and terminationGracePeriodSeconds correctly when set
• Default values produce no change in rendered output (no lifecycle or terminationGracePeriodSeconds in the manifest)

[emyller]

Thank you for the contribution! This is helpful and much appreciated.