Add app version metadata to Project settings (fixes #167)

[Flamki]

Closes #167

Summary

• Add a new admin-protected backend route system.version exposing:
  • version
  • commit
  • buildDate
• Display this metadata in Settings > Project under a new Application card (admin only).
• Wire Docker/build metadata into runtime env:
  • APP_VERSION
  • APP_COMMIT
  • APP_BUILD_DATE
• Align FastAPI env usage to FASTAPI_PORT across backend/CLI/docs/compose/workflow.

Why

As requested in #167, admins need to identify exactly which app build is running, including commit SHA in Docker deployments.

Testing

• Live smoke test passed:
  1. Started backend with:
     • APP_VERSION=1.2.3
     • APP_COMMIT=abc1234
     • APP_BUILD_DATE=2026-02-11T00:00:00Z
  2. Signed up an admin user via /api/auth/sign-up/email
  3. Confirmed project/admin context via /api/trpc/project.getCurrent
  4. Queried /api/trpc/system.version with auth cookie and got:

     {"version":"1.2.3","commit":"abc1234","buildDate":"2026-02-11T00:00:00Z"}

Notes

• Full repo lint/typecheck has existing unrelated failures; this change was validated with runtime smoke testing on the affected path.