Replace hand-rolled feedback.py with make_feedback_router() from
circuitforge_core.api.feedback. Update tests to mount the shared
router on a minimal FastAPI app and mock at the core module level.
- feedback.py: add GET /feedback/status endpoint (returns {enabled: bool})
so frontend can probe on mount instead of optimistic-enable; remove
unused get_db import
- FeedbackButton.vue: probe /feedback/status on mount, start hidden;
drop redundant 503-hide path (status probe makes it redundant)
- pyproject.toml: declare requests>=2.31 (used by feedback.py Forgejo calls)
- tests/api/test_feedback.py: 7 tests — status endpoint (no-token, token,
demo mode), POST 503/403, happy path with mocked Forgejo, 502 on error
