feat: refactor super admin to use is_super_admin flag and enhance site deletion logic

- Changed super admin detection from role-based to `is_super_admin` flag in AdminUser model
- Added `requireDefaultAdminSiteId()` method to throw validation error when no integration site exists
- Enhanced site deletion to migrate platform role bindings to fallback site and auto-delete site-specific admin accounts
- Made agent line code optional with auto-generation fallback using `{site_code}-agent-{counter}` format

app/Services/Admin/AdminDashboardSnapshotBuilder.php

@@ -17,6 +17,7 @@ use App\Support\AdminDataScope;
 use App\Support\AdminScopeContext;
 use App\Support\AdminAgentScope;
 use App\Support\AdminScopeContextResolver;
+use App\Support\SitePlatformRole;
 use Illuminate\Database\Eloquent\Builder as EloquentBuilder;
 
 /**
@@ -30,6 +31,7 @@ final class AdminDashboardSnapshotBuilder
         private readonly DrawHallSnapshotBuilder $hallSnapshot,
         private readonly AdminReportQueryService $reportQuery,
         private readonly AgentDashboardOverviewBuilder $agentOverview,
+        private readonly SiteDashboardOverviewBuilder $siteOverview,
     ) {}
 
     /** @return array<string, mixed> */
@@ -57,10 +59,13 @@ final class AdminDashboardSnapshotBuilder
                 'wallet_transfer_view' => $canWallet,
             ],
             'agent_overview' => null,
+            'site_overview' => null,
         ];
 
         if ($admin->primaryAgentNode() !== null) {
             $out['agent_overview'] = $this->agentOverview->build($admin);
+        } elseif (SitePlatformRole::userHasSiteAdminRole($admin)) {
+            $out['site_overview'] = $this->siteOverview->build($admin, $scope);
         }
 
         if ($canDraw) {