fix(api): revert auth/type regressions from standalone sync, keep email-in feature only

- Revert auth/dependencies.py to cookie+Bearer dual auth with str user IDs
- Add GET /auth/me/email-in-address endpoint for receipt email routing
- Update User model: add email_inbound_token, change id/store_id/user_id to str
- Update AuthService and UserResponse to use str user IDs
- Update route count test: 33 -> 34 routes
- Restore e2e test for email-in-address endpoint

Co-Authored-By: Paperclip <noreply@paperclip.ing>

tests/test_middleware/test_error_handler.py

@@ -15,12 +15,11 @@ async def test_404_returns_structured_error(client):
 
 
 @pytest.mark.asyncio
-async def test_validation_error_returns_422_with_field_errors(client, auth_headers):
+async def test_validation_error_returns_422_with_field_errors(client):
     """Invalid request body should return structured validation errors."""
-    resp = await client.patch(
-        "/auth/me",
-        headers=auth_headers,
-        json={"display_name": ""},
+    resp = await client.post(
+        "/auth/register",
+        json={"email": "not-an-email", "password": "short", "display_name": ""},
     )
     assert resp.status_code == 422
     body = resp.json()