Implement release-please for automated versioning & releases

[DevSecNinja]

Goal

Adopt the central release-please setup for consistent, automated semantic versioning and GitHub Releases.

Priority tier: 1
Rationale: Python app; the 88 'db-*' tags are data snapshots, version the code separately.

What's needed

• Add caller workflow .github/workflows/release-please.yml referencing DevSecNinja/.github/.github/workflows/release-please.yml
• Add release-please-config.json
• Add .release-please-manifest.json
• Configure RELEASE_PLEASE_APP_ID variable and RELEASE_PLEASE_APP_PRIVATE_KEY secret
• Ensure commits follow Conventional Commits

See onboarding docs: DevSecNinja/.github → docs/release-please-onboarding.md

Created as part of a cross-repo release-please consistency review.