feat(audit): make worker runtime ready

[man4ish]

PR-B0 — Security Audit Runtime Readiness

Summary

Makes the existing security-audit worker deployable and observable in the platform runtime.

Changes

• add container health check to the security-audit API
• add real Redis/MySQL worker integration tests

No Interaction domain implementation is included.

Validation

• real Redis → worker → MySQL integration tests pass
• full security-audit test suite passes
• Docker build passes
• git diff --check passes

Scope boundaries

This PR does NOT:

• add Interaction schema/API/UI
• modify authentication/session behavior
• modify Control Center
• introduce a new microservice
• introduce another correlation ID
• modify existing audit producers

Known follow-ups

Two findings were intentionally left outside PR-B0:

1. the currently published :latest image is stale and requires a separate release/tagging action
2. API Gateway audit events currently do not fully match the security-audit event schema and require a separate gateway PR

Neither is changed here.