feat: add show_in_legal to admin content page editor

- Add "Show in Legal" checkbox to content page editor UI
- Update API schemas (ContentPageCreate, ContentPageUpdate, ContentPageResponse)
- Add show_in_legal parameter to service methods (create_page, update_page, etc.)
- Fix ContentPageNotFoundException to pass identifier correctly
- Fix UnauthorizedContentPageAccessException to use correct AuthorizationException API
- Add comprehensive unit tests for ContentPageService (35 tests)
- Add content page fixtures for testing
- Update CMS documentation with navigation categories diagram

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

app/exceptions/content_page.py

@@ -23,7 +23,11 @@ class ContentPageNotFoundException(ResourceNotFoundException):
             message = f"Content page not found: {identifier}"
         else:
             message = "Content page not found"
-        super().__init__(message=message, resource_type="content_page")
+        super().__init__(
+            message=message,
+            resource_type="content_page",
+            identifier=str(identifier) if identifier else "unknown",
+        )
 
 
 class ContentPageAlreadyExistsException(ConflictException):
@@ -61,7 +65,8 @@ class UnauthorizedContentPageAccessException(AuthorizationException):
     def __init__(self, action: str = "access"):
         super().__init__(
             message=f"Cannot {action} content pages from other vendors",
-            required_permission=f"content_page:{action}",
+            error_code="CONTENT_PAGE_ACCESS_DENIED",
+            details={"required_permission": f"content_page:{action}"},
         )
 
 
@@ -71,7 +76,8 @@ class VendorNotAssociatedException(AuthorizationException):
     def __init__(self):
         super().__init__(
             message="User is not associated with a vendor",
-            required_permission="vendor:member",
+            error_code="VENDOR_NOT_ASSOCIATED",
+            details={"required_permission": "vendor:member"},
         )