feat: production routing support for subdomain and custom domain modes

Double-mount store routes at /store/* and /store/{store_code}/* so the
same handlers work in dev path-based, prod path-based, prod subdomain,
and prod custom-domain modes.  Wire StorePlatform.custom_subdomain into
StoreContextMiddleware for per-platform subdomain overrides.  Add admin
custom-domain management UI, fix stale /shop/ reset link, add
/merchants/ to reserved paths, and server-render window.STORE_CODE for
JS that previously parsed the URL.

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

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

@@ -8,7 +8,7 @@ Store pages for:
 - Program settings
 - Stats dashboard
 
-Routes follow the standard store convention: /{store_code}/loyalty/...
+Routes follow the standard store convention: /loyalty/...
 so they match the menu URLs in definition.py.
 """
 
@@ -18,7 +18,11 @@ from fastapi import APIRouter, Depends, Path, Request
 from fastapi.responses import HTMLResponse, RedirectResponse
 from sqlalchemy.orm import Session
 
-from app.api.deps import get_current_store_from_cookie_or_header, get_db
+from app.api.deps import (
+    get_current_store_from_cookie_or_header,
+    get_db,
+    get_resolved_store_code,
+)
 from app.modules.core.services.platform_settings_service import (
     platform_settings_service,
 )
@@ -86,12 +90,12 @@ def get_store_context(
 
 
 @router.get(
-    "/{store_code}/loyalty",
+    "/loyalty",
     response_class=RedirectResponse,
     include_in_schema=False,
 )
 async def store_loyalty_root(
-    store_code: str = Path(..., description="Store code"),
+    store_code: str = Depends(get_resolved_store_code),
     current_user: User = Depends(get_current_store_from_cookie_or_header),
 ):
     """
@@ -110,13 +114,13 @@ async def store_loyalty_root(
 
 
 @router.get(
-    "/{store_code}/loyalty/terminal",
+    "/loyalty/terminal",
     response_class=HTMLResponse,
     include_in_schema=False,
 )
 async def store_loyalty_terminal(
     request: Request,
-    store_code: str = Path(..., description="Store code"),
+    store_code: str = Depends(get_resolved_store_code),
     current_user: User = Depends(get_current_store_from_cookie_or_header),
     db: Session = Depends(get_db),
 ):
@@ -136,13 +140,13 @@ async def store_loyalty_terminal(
 
 
 @router.get(
-    "/{store_code}/loyalty/cards",
+    "/loyalty/cards",
     response_class=HTMLResponse,
     include_in_schema=False,
 )
 async def store_loyalty_cards(
     request: Request,
-    store_code: str = Path(..., description="Store code"),
+    store_code: str = Depends(get_resolved_store_code),
     current_user: User = Depends(get_current_store_from_cookie_or_header),
     db: Session = Depends(get_db),
 ):
@@ -157,13 +161,13 @@ async def store_loyalty_cards(
 
 
 @router.get(
-    "/{store_code}/loyalty/cards/{card_id}",
+    "/loyalty/cards/{card_id}",
     response_class=HTMLResponse,
     include_in_schema=False,
 )
 async def store_loyalty_card_detail(
     request: Request,
-    store_code: str = Path(..., description="Store code"),
+    store_code: str = Depends(get_resolved_store_code),
     card_id: int = Path(..., description="Loyalty card ID"),
     current_user: User = Depends(get_current_store_from_cookie_or_header),
     db: Session = Depends(get_db),
@@ -184,13 +188,13 @@ async def store_loyalty_card_detail(
 
 
 @router.get(
-    "/{store_code}/loyalty/stats",
+    "/loyalty/stats",
     response_class=HTMLResponse,
     include_in_schema=False,
 )
 async def store_loyalty_stats(
     request: Request,
-    store_code: str = Path(..., description="Store code"),
+    store_code: str = Depends(get_resolved_store_code),
     current_user: User = Depends(get_current_store_from_cookie_or_header),
     db: Session = Depends(get_db),
 ):
@@ -210,13 +214,13 @@ async def store_loyalty_stats(
 
 
 @router.get(
-    "/{store_code}/loyalty/enroll",
+    "/loyalty/enroll",
     response_class=HTMLResponse,
     include_in_schema=False,
 )
 async def store_loyalty_enroll(
     request: Request,
-    store_code: str = Path(..., description="Store code"),
+    store_code: str = Depends(get_resolved_store_code),
     current_user: User = Depends(get_current_store_from_cookie_or_header),
     db: Session = Depends(get_db),
 ):