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/admin/__init__.py

@@ -49,7 +49,7 @@ from . import (
     code_quality,
     companies,
     # content_pages - moved to app.modules.cms.routes.api.admin
-    customers,
+    # customers - moved to app.modules.customers.routes.admin
     dashboard,
     email_templates,
     features,
@@ -92,6 +92,9 @@ from app.modules.marketplace.routes.api.admin import admin_letzshop_router as le
 # CMS module router
 from app.modules.cms.routes.api.admin import router as cms_admin_router
 
+# Customers module router
+from app.modules.customers.routes.admin import admin_router as customers_admin_router
+
 # Create admin router
 router = APIRouter()
 
@@ -149,8 +152,9 @@ router.include_router(users.router, tags=["admin-users"])
 # Include admin user management endpoints (super admin only)
 router.include_router(admin_users.router, tags=["admin-admin-users"])
 
-# Include customer management endpoints
-router.include_router(customers.router, tags=["admin-customers"])
+# Include customers module router (with module access control)
+router.include_router(customers_admin_router, tags=["admin-customers"])
+# Legacy: router.include_router(customers.router, tags=["admin-customers"])
 
 
 # ============================================================================