refactor(customers): migrate routes to module with auto-discovery

- Move customer route implementations to app/modules/customers/routes/
- Convert legacy app/api/v1/{admin,vendor}/customers.py to re-exports
- Update router registrations to use module routers with access control
- Fix CustomerListResponse pagination (page/per_page/total_pages)
- Update URL routing docs to use storefront consistently
- Fix mkdocs.yml nav references (shop -> storefront)
- Fix broken doc links in logging.md and cdn-fallback-strategy.md

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

app/api/v1/vendor/__init__.py

@@ -35,7 +35,7 @@ from . import (
     auth,
     billing,
     # content_pages - moved to app.modules.cms.routes.api.vendor
-    customers,
+    # customers - moved to app.modules.customers.routes.vendor
     dashboard,
     email_settings,
     email_templates,
@@ -71,6 +71,9 @@ from app.modules.marketplace.routes.api.vendor import vendor_letzshop_router as
 # CMS module router
 from app.modules.cms.routes.api.vendor import router as cms_vendor_router
 
+# Customers module router
+from app.modules.customers.routes.vendor import vendor_router as customers_vendor_router
+
 # Create vendor router
 router = APIRouter()
 
@@ -104,7 +107,11 @@ router.include_router(orders_exceptions_router, tags=["vendor-order-exceptions"]
 # Legacy: router.include_router(order_item_exceptions.router, tags=["vendor-order-exceptions"])
 
 router.include_router(invoices.router, tags=["vendor-invoices"])
-router.include_router(customers.router, tags=["vendor-customers"])
+
+# Include customers module router (with module access control)
+router.include_router(customers_vendor_router, tags=["vendor-customers"])
+# Legacy: router.include_router(customers.router, tags=["vendor-customers"])
+
 router.include_router(team.router, tags=["vendor-team"])
 
 # Include inventory module router (with module access control)