fix: move email-in-address endpoint from /auth to /api/v1 prefix

The GET /me/email-in-address endpoint was unreachable because the Gateway
HTTPRoute routes all /auth/* traffic to Better-Auth (port 3001), not the
API service. This change:
- Moves the endpoint from the /auth router to a new /api/v1/me/ router
- Adds EmailInAddressResponse schema and get_email_in_address service method
- Updates Settings.tsx to call /api/v1/me/email-in-address

Fixes CAR-445.

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

src/cartsnitch_api/main.py

@@ -18,6 +18,7 @@ from cartsnitch_api.routes.purchases import router as purchases_router
 from cartsnitch_api.routes.scraping import router as scraping_router
 from cartsnitch_api.routes.shopping import router as shopping_router
 from cartsnitch_api.routes.stores import router as stores_router
+from cartsnitch_api.routes.user import router as user_router
 
 
 @asynccontextmanager
@@ -49,6 +50,7 @@ def create_app() -> FastAPI:
 
     # Data endpoints mounted under /api/v1
     v1_router = APIRouter(prefix="/api/v1")
+    v1_router.include_router(user_router)
     v1_router.include_router(stores_router)
     v1_router.include_router(purchases_router)
     v1_router.include_router(products_router)