Stability checkpoint UI — CI runner consolidation

CI fixes :
- Route all jobs to macbook-local (group-level runner 52880082).
  Previous main pipelines failed with ci_quota_exceeded on SaaS shared runners.
- Red watchtower icon for project avatar.

Validation : UI main pipeline #480 green
- unit-tests + unit-tests:node20 + lint:circular-deps + build:production ✓
- bundle-size-check + typedoc + docker-build ✓
- trivy + sbom + grype + dockle + cosign:sign ✓
- e2e:kind ✓ (Playwright + Chromium)