feat: platform-aware storefront routing and billing improvements

Overhaul storefront URL routing to be platform-aware:
- Dev: /platforms/{code}/storefront/{store_code}/
- Prod: subdomain.platform.lu/ (internally rewritten to /storefront/)
- Add subdomain detection in PlatformContextMiddleware
- Add /storefront/ path rewrite for prod mode (subdomain/custom domain)
- Remove all silent platform fallbacks (platform_id=1)
- Add require_platform dependency for clean endpoint validation
- Update route registration, templates, module definitions, base_url calc
- Update StoreContextMiddleware for /storefront/ path detection
- Remove /stores/ from FrontendDetector STOREFRONT_PATH_PREFIXES

Billing service improvements:
- Add store_platform_sync_service to keep store_platforms in sync
- Make tier lookups platform-aware across billing services
- Add tiers for all platforms in seed data
- Add demo subscriptions to seed

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/modules/cms/definition.py

@@ -39,7 +39,9 @@ def _get_platform_context(request: Any, db: Any, platform: Any) -> dict[str, Any
     """
     from app.modules.cms.services import content_page_service
 
-    platform_id = platform.id if platform else 1
+    if not platform:
+        return {"header_pages": [], "footer_pages": [], "legal_pages": []}
+    platform_id = platform.id
 
     header_pages = []
     footer_pages = []
@@ -73,7 +75,9 @@ def _get_storefront_context(request: Any, db: Any, platform: Any) -> dict[str, A
     from app.modules.cms.services import content_page_service
 
     store = getattr(request.state, "store", None)
-    platform_id = platform.id if platform else 1
+    if not platform:
+        return {"header_pages": [], "footer_pages": [], "legal_pages": []}
+    platform_id = platform.id
 
     header_pages = []
     footer_pages = []

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

@@ -11,6 +11,7 @@ import logging
 from fastapi import APIRouter, Depends, Request
 from sqlalchemy.orm import Session
 
+from app.api.deps import require_platform
 from app.core.database import get_db
 from app.modules.cms.schemas import (
     ContentPageListItem,
@@ -29,7 +30,11 @@ logger = logging.getLogger(__name__)
 
 # public - storefront content pages are publicly accessible
 @router.get("/navigation", response_model=list[ContentPageListItem])
-def get_navigation_pages(request: Request, db: Session = Depends(get_db)):
+def get_navigation_pages(
+    request: Request,
+    platform=Depends(require_platform),
+    db: Session = Depends(get_db),
+):
     """
     Get list of content pages for navigation (footer/header).
 
@@ -37,9 +42,8 @@ def get_navigation_pages(request: Request, db: Session = Depends(get_db)):
     Returns store overrides + platform defaults.
     """
     store = getattr(request.state, "store", None)
-    platform = getattr(request.state, "platform", None)
     store_id = store.id if store else None
-    platform_id = platform.id if platform else 1
+    platform_id = platform.id
 
     # Get all published pages for this store
     pages = content_page_service.list_pages_for_store(
@@ -59,7 +63,12 @@ def get_navigation_pages(request: Request, db: Session = Depends(get_db)):
 
 
 @router.get("/{slug}", response_model=PublicContentPageResponse)
-def get_content_page(slug: str, request: Request, db: Session = Depends(get_db)):
+def get_content_page(
+    slug: str,
+    request: Request,
+    platform=Depends(require_platform),
+    db: Session = Depends(get_db),
+):
     """
     Get a specific content page by slug.
 
@@ -67,9 +76,8 @@ def get_content_page(slug: str, request: Request, db: Session = Depends(get_db))
     Returns store override if exists, otherwise platform default.
     """
     store = getattr(request.state, "store", None)
-    platform = getattr(request.state, "platform", None)
     store_id = store.id if store else None
-    platform_id = platform.id if platform else 1
+    platform_id = platform.id
 
     page = content_page_service.get_page_for_store_or_raise(
         db,

app/modules/cms/routes/pages/platform.py

@@ -91,8 +91,9 @@ async def homepage(
     if store:
         logger.debug(f"[HOMEPAGE] Store detected: {store.subdomain}")
 
-        # Get platform_id (use platform from context or default to 1 for OMS)
-        platform_id = platform.id if platform else 1
+        if not platform:
+            raise HTTPException(status_code=400, detail="Platform context required")
+        platform_id = platform.id
 
         # Try to find store landing page (slug='landing' or 'home')
         landing_page = content_page_service.get_page_for_store(
@@ -133,21 +134,19 @@ async def homepage(
             else "unknown"
         )
 
-        if access_method == "path":
-            full_prefix = (
-                store_context.get("full_prefix", "/store/")
-                if store_context
-                else "/store/"
-            )
+        if access_method == "path" and platform:
             return RedirectResponse(
-                url=f"{full_prefix}{store.subdomain}/storefront/", status_code=302
+                url=f"/platforms/{platform.code}/storefront/{store.store_code}/",
+                status_code=302,
             )
-        # Domain/subdomain - redirect to /storefront/
-        return RedirectResponse(url="/storefront/", status_code=302)
+        # Domain/subdomain - root is storefront
+        return RedirectResponse(url="/", status_code=302)
 
     # Scenario 2: Platform marketing site (no store)
     # Load platform homepage from CMS (slug='home')
-    platform_id = platform.id if platform else 1
+    if not platform:
+        raise HTTPException(status_code=400, detail="Platform context required")
+    platform_id = platform.id
 
     cms_homepage = content_page_service.get_platform_page(
         db, platform_id=platform_id, slug="home", include_unpublished=False
@@ -227,9 +226,10 @@ async def content_page(
     This is a catch-all route for dynamic content pages managed via the admin CMS.
     Platform pages have store_id=None and is_platform_page=True.
     """
-    # Get platform from middleware (default to OMS platform_id=1)
     platform = getattr(request.state, "platform", None)
-    platform_id = platform.id if platform else 1
+    if not platform:
+        raise HTTPException(status_code=400, detail="Platform context required")
+    platform_id = platform.id
 
     # Load platform marketing page from database
     page = content_page_service.get_platform_page(

app/modules/cms/routes/pages/store.py

@@ -184,7 +184,9 @@ async def store_content_page(
     store = getattr(request.state, "store", None)
     platform = getattr(request.state, "platform", None)
     store_id = store.id if store else None
-    platform_id = platform.id if platform else 1
+    if not platform:
+        raise HTTPException(status_code=400, detail="Platform context required")
+    platform_id = platform.id
 
     # Load content page from database (store override → platform default)
     page = content_page_service.get_page_for_store(

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

@@ -66,7 +66,9 @@ async def generic_content_page(
     store = getattr(request.state, "store", None)
     platform = getattr(request.state, "platform", None)
     store_id = store.id if store else None
-    platform_id = platform.id if platform else 1  # Default to OMS
+    if not platform:
+        raise HTTPException(status_code=400, detail="Platform context required")
+    platform_id = platform.id
 
     # Load content page from database (store override -> store default)
     page = content_page_service.get_page_for_store(