fix: admin pages stuck on infinite loading - reset data fields when auth transitions

Symptoms: After login, admin pages showed loading spinner forever. Root cause:
OnInitializedAsync in 11 admin pages (Dashboard, Blog, Inquiries, Clients,
Announcements, FAQs, TaxProfiles, ConsultingActivities, TaxFilingSchedules,
Contracts, RevenueTrackings) checked AuthStateTask and loaded data only if
authState.User.Identity?.IsAuthenticated == true. If that condition was ever
false (e.g., transient auth state resolution timing), the page never reset
its data collection from null → []. AdminDataPanel uses "Loading={item == null}"
as its loading predicate, so null persisted indefinitely.

Fix: Always reset the data collection, whether the auth check passes or fails:
- AuthStateTask != null && IsAuthenticated == true: load data (existing)
- AuthStateTask != null && IsAuthenticated == false: set data = [] (new else)
- AuthStateTask == null: set data = [] (new else)

This ensures AdminDataPanel's "Loading" condition becomes false on all code
paths, not just the success case.

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

src/TaxBaik.Web.Client/Components/Admin/Pages/Announcements/AnnouncementList.razor

@@ -129,6 +129,14 @@
             {
                 await LoadAsync();
             }
+            else
+            {
+                announcements = [];
+            }
+        }
+        else
+        {
+            announcements = [];
         }
     }
 

src/TaxBaik.Web.Client/Components/Admin/Pages/Blog/BlogList.razor

@@ -95,6 +95,14 @@
             {
                 await LoadPosts();
             }
+            else
+            {
+                isLoading = false;
+            }
+        }
+        else
+        {
+            isLoading = false;
         }
     }
 

src/TaxBaik.Web.Client/Components/Admin/Pages/Clients/ClientList.razor

@@ -147,6 +147,14 @@
             {
                 await LoadAsync();
             }
+            else
+            {
+                clients = [];
+            }
+        }
+        else
+        {
+            clients = [];
         }
     }
 

src/TaxBaik.Web.Client/Components/Admin/Pages/ConsultingActivities.razor

@@ -145,6 +145,14 @@
             {
                 await LoadData();
             }
+            else
+            {
+                activities = [];
+            }
+        }
+        else
+        {
+            activities = [];
         }
     }
 

src/TaxBaik.Web.Client/Components/Admin/Pages/Contracts.razor

@@ -176,6 +176,14 @@ else
                 await LoadData();
                 PrepareCreate();
             }
+            else
+            {
+                contracts = [];
+            }
+        }
+        else
+        {
+            contracts = [];
         }
     }
 

src/TaxBaik.Web.Client/Components/Admin/Pages/Dashboard.razor

@@ -185,6 +185,17 @@
                     isLoading = false;
                 }
             }
+            else
+            {
+                // AuthorizeRouteView already gates this page, so this branch is
+                // only a transient auth-state resolution timing gap - but without
+                // resetting isLoading here, AdminDataPanel would spin forever.
+                isLoading = false;
+            }
+        }
+        else
+        {
+            isLoading = false;
         }
     }
 

src/TaxBaik.Web.Client/Components/Admin/Pages/Faqs/FaqList.razor

@@ -133,6 +133,14 @@
             {
                 await LoadAsync();
             }
+            else
+            {
+                faqs = [];
+            }
+        }
+        else
+        {
+            faqs = [];
         }
     }
 

src/TaxBaik.Web.Client/Components/Admin/Pages/Inquiries/InquiryList.razor

@@ -52,6 +52,14 @@
             {
                 await LoadData();
             }
+            else
+            {
+                isLoading = false;
+            }
+        }
+        else
+        {
+            isLoading = false;
         }
     }
 

src/TaxBaik.Web.Client/Components/Admin/Pages/RevenueTrackings.razor

@@ -141,6 +141,14 @@
             {
                 await LoadData();
             }
+            else
+            {
+                revenues = [];
+            }
+        }
+        else
+        {
+            revenues = [];
         }
     }
 

src/TaxBaik.Web.Client/Components/Admin/Pages/TaxFilingSchedules.razor

@@ -198,6 +198,14 @@ else
                 await LoadData();
                 PrepareCreate();
             }
+            else
+            {
+                schedules = [];
+            }
+        }
+        else
+        {
+            schedules = [];
         }
     }
 

src/TaxBaik.Web.Client/Components/Admin/Pages/TaxProfiles.razor

@@ -151,6 +151,14 @@ else
                 await LoadData();
                 PrepareCreate();
             }
+            else
+            {
+                profiles = [];
+            }
+        }
+        else
+        {
+            profiles = [];
         }
     }