refactor: replace internal require2fa app with PyPI package

## Migration to PyPI Package
Successfully migrated from internal require2fa app to published
django-allauth-require2fa package (v1.2.0) from PyPI.

## Changes Made
- Add django-allauth-require2fa to pyproject.toml dependencies
- Keep require2fa in INSTALLED_APPS (package installs as require2fa module)
- Keep require2fa.middleware.Require2FAMiddleware path (same import)
- Verified existing TwoFactorConfig data is preserved and accessible

## Benefits
- ✅ Use community-maintained package instead of internal code
- ✅ Simplified maintenance and updates via PyPI
- ✅ Zero configuration changes needed (seamless transition)
- ✅ Existing 2FA settings preserved (required=True verified)

## Next Steps
The internal src/require2fa/ directory can now be safely removed
since the PyPI package provides identical functionality.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: heysamtexas

pyproject.toml

@@ -31,6 +31,7 @@ dependencies = [
     "whitenoise==6.9.0",
     "PyJWT==2.10.1",
     "django-allauth[mfa,socialaccount]",
+    "django-allauth-require2fa",
 ]
 
 [project.optional-dependencies]