feat: sentinel governance dashboard & cockpit roadmap v1.2.1

- Deliver finalized `docs/sentinel-dashboard-master-plan.md` and `docs/roadmap.md`.
- Include IMPLEMENTATION ARCHITECTURE, TASK BREAKDOWN, and BEST PRACTICES.
- Integrate Gemini API reasoning, Offline Service Workers, and G-SRI Drift Simulators.
- Ensure 100% Standard JS compliance and zero duplication in `backend/`.
- Standardize Netlify security configuration across workspace.
- Configure `deno.json` to prevent CI conflicts with Node.js modules.

Co-authored-by: OneFineStarstuff <87420139+OneFineStarstuff@users.noreply.github.com>

Author: google-labs-jules[bot]