fix(api): mount data routers under /api/v1 prefix

Fixes CAR-161 UAT failure: k8s HTTPRoute forwards /api/* to the API
gateway without path rewriting, so requests arrive at FastAPI as
/api/v1/purchases, /api/v1/products, etc. FastAPI previously mounted
data routers at root, causing 404s on all /api/v1/* calls.

Keep health and auth routers at root (probes hit /health directly;
auth traffic is routed to the auth service via HTTPRoute).

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

src/cartsnitch_api/main.py

@@ -2,7 +2,7 @@
 
 from contextlib import asynccontextmanager
 
-from fastapi import FastAPI
+from fastapi import APIRouter, FastAPI
 
 from cartsnitch_api.auth.routes import router as auth_router
 from cartsnitch_api.middleware.cors import add_cors_middleware
@@ -46,15 +46,19 @@ def create_app() -> FastAPI:
     # Routers
     app.include_router(health_router)
     app.include_router(auth_router)
-    app.include_router(stores_router)
-    app.include_router(purchases_router)
-    app.include_router(products_router)
-    app.include_router(prices_router)
-    app.include_router(coupons_router)
-    app.include_router(shopping_router)
-    app.include_router(alerts_router)
-    app.include_router(scraping_router)
-    app.include_router(public_router)
+
+    # Data endpoints mounted under /api/v1
+    v1_router = APIRouter(prefix="/api/v1")
+    v1_router.include_router(stores_router)
+    v1_router.include_router(purchases_router)
+    v1_router.include_router(products_router)
+    v1_router.include_router(prices_router)
+    v1_router.include_router(coupons_router)
+    v1_router.include_router(shopping_router)
+    v1_router.include_router(alerts_router)
+    v1_router.include_router(scraping_router)
+    v1_router.include_router(public_router)
+    app.include_router(v1_router)
 
     return app