refactor: rename shop to storefront throughout codebase

Rename "shop" to "storefront" as not all platforms sell items -
storefront is a more accurate term for the customer-facing interface.

Changes:
- Rename app/api/v1/shop/ → app/api/v1/storefront/
- Rename app/routes/shop_pages.py → app/routes/storefront_pages.py
- Rename app/modules/cms/routes/api/shop.py → storefront.py
- Rename tests/integration/api/v1/shop/ → storefront/
- Update API prefix from /api/v1/shop to /api/v1/storefront
- Update route tags from shop-* to storefront-*
- Rename get_shop_context() → get_storefront_context()
- Update architecture rules to reference storefront paths
- Update all test API endpoint paths

This is Phase 2 of the storefront module restructure plan.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/modules/cms/routes/api/__init__.py

@@ -5,11 +5,11 @@ CMS module API routes.
 Provides REST API endpoints for content page management:
 - Admin API: Full CRUD for platform administrators
 - Vendor API: Vendor-scoped CRUD with ownership checks
-- Shop API: Public read-only access for storefronts
+- Storefront API: Public read-only access for storefronts
 """
 
 from app.modules.cms.routes.api.admin import router as admin_router
 from app.modules.cms.routes.api.vendor import router as vendor_router
-from app.modules.cms.routes.api.shop import router as shop_router
+from app.modules.cms.routes.api.storefront import router as storefront_router
 
-__all__ = ["admin_router", "vendor_router", "shop_router"]
+__all__ = ["admin_router", "vendor_router", "storefront_router"]

app/modules/cms/routes/api/storefront.py

@@ -1,8 +1,8 @@
-# app/modules/cms/routes/api/shop.py
+# app/modules/cms/routes/api/storefront.py
 """
-Shop Content Pages API (Public)
+Storefront Content Pages API (Public)
 
-Public endpoints for retrieving content pages in shop frontend.
+Public endpoints for retrieving content pages in storefront.
 No authentication required.
 """