feat: add platform detail/edit admin UI and service enhancements

- Add platform detail and edit admin pages with templates and JS
- Add ContentPageService methods: list_all_platform_pages, list_all_vendor_defaults
- Deprecate /admin/platform-homepage route (redirects to /admin/platforms)
- Add migration to fix content_page nullable columns
- Refine platform and vendor context middleware
- Add platform context middleware unit tests
- Update platforms.js with improved functionality
- Add section-based homepage plan documentation

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

middleware/vendor_context.py

@@ -91,7 +91,7 @@ class VendorContextManager:
 
         # Method 3: Path-based detection (/vendor/vendorname/ or /vendors/vendorname/)
         # Support BOTH patterns for flexibility
-        if path.startswith("/vendor/") or path.startswith("/vendors/"):
+        if path.startswith(("/vendor/", "/vendors/")):
             # Determine which pattern
             if path.startswith("/vendors/"):
                 prefix_len = len("/vendors/")
@@ -133,8 +133,8 @@ class VendorContextManager:
                 vendor_domain = (
                     db.query(VendorDomain)
                     .filter(VendorDomain.domain == domain)
-                    .filter(VendorDomain.is_active == True)
-                    .filter(VendorDomain.is_verified == True)
+                    .filter(VendorDomain.is_active.is_(True))
+                    .filter(VendorDomain.is_verified.is_(True))
                     .first()
                 )
 
@@ -157,7 +157,7 @@ class VendorContextManager:
             vendor = (
                 db.query(Vendor)
                 .filter(func.lower(Vendor.subdomain) == subdomain.lower())
-                .filter(Vendor.is_active == True)
+                .filter(Vendor.is_active.is_(True))
                 .first()
             )
 
@@ -204,10 +204,7 @@ class VendorContextManager:
         if host.startswith("admin."):
             return True
 
-        if path.startswith("/admin"):
-            return True
-
-        return False
+        return path.startswith("/admin")
 
     @staticmethod
     def is_api_request(request: Request) -> bool:
@@ -263,9 +260,7 @@ class VendorContextManager:
 
             # Method 1: Path-based detection from referer path
             # /vendors/wizamart/shop/products → wizamart
-            if referer_path.startswith("/vendors/") or referer_path.startswith(
-                "/vendor/"
-            ):
+            if referer_path.startswith(("/vendors/", "/vendor/")):
                 prefix = (
                     "/vendors/" if referer_path.startswith("/vendors/") else "/vendor/"
                 )
@@ -384,10 +379,7 @@ class VendorContextManager:
         if any(path.startswith(static_path) for static_path in static_paths):
             return True
 
-        if "favicon.ico" in path:
-            return True
-
-        return False
+        return "favicon.ico" in path
 
 
 class VendorContextMiddleware(BaseHTTPMiddleware):