Production code shouldn't branch on `"pytest" in sys.modules` — it's
fragile and couples db.py to test tooling. Instead, conftest.py now
builds its own dedicated NullPool engine directly from settings, used
only for the drop_all/create_all reset and the get_db override. The
production engine in app/db.py is untouched and never exercised during
tests, so this fully preserves the event-loop fix while keeping prod
code test-agnostic.
- Restored .worktrees/ line that was lost when .gitignore was overwritten in commit 1736dd0
- Added backend/tests/__init__.py as a package marker (was untracked on disk)
- Test suite verified: backend tests pass (1/1)
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
