Updated Docker healthcheck to use the correct /api/v1/health endpoint
created in P1.6 instead of the old /health endpoint.
Note: Dockerfile already implements multi-stage build best practices:
- Builder stage: golang:1.23-alpine with dependency caching
- Runtime stage: alpine:latest (minimal footprint)
- Static binary: CGO_ENABLED=0 for portability
- Size optimization: -ldflags="-w -s" strips debug info
- Security: Non-root user (app:1001)
- Health check: 30s interval, 3 retries
Image size: ~15-20MB (vs ~150MB+ without multi-stage)
Fixes: P3.2 from audit AUDIT_TEMP_29_01_2026.md
