feat: implement multi-tenancy support across knowledge services and normalize TenantId to string type.

src/NexusReader.UI.Shared/Components/Molecules/GroundednessBadge.razor

@@ -1,7 +1,10 @@
 @using MediatR
 @using NexusReader.Application.Commands.AI
+@using NexusReader.Application.Abstractions.Services
 @using NexusReader.UI.Shared.Components.Atoms
+@using Microsoft.AspNetCore.Components.Authorization
 @inject IMediator Mediator
+@inject AuthenticationStateProvider AuthProvider
 
 <div class="groundedness-badge @GetStatusClass()" title="@_result?.Rationale">
     @if (_isChecking)
@@ -24,16 +27,29 @@
         border-radius: 12px;
         font-size: 0.75rem;
         font-weight: 600;
-        background: rgba(255,255,255,0.05);
-        border: 1px solid rgba(255,255,255,0.1);
+        background: rgba(255, 255, 255, 0.05);
+        border: 1px solid rgba(255, 255, 255, 0.1);
         transition: all 0.3s ease;
     }
 
-    .groundedness-badge.status-high { color: var(--nexus-neon); border-color: var(--nexus-neon); }
-    .groundedness-badge.status-medium { color: #ffaa00; border-color: #ffaa00; }
-    .groundedness-badge.status-low { color: #ff4444; border-color: #ff4444; }
+    .groundedness-badge.status-high {
+        color: var(--nexus-neon);
+        border-color: var(--nexus-neon);
+    }
 
-    .shimmer { opacity: 0.6; }
+    .groundedness-badge.status-medium {
+        color: #ffaa00;
+        border-color: #ffaa00;
+    }
+
+    .groundedness-badge.status-low {
+        color: #ff4444;
+        border-color: #ff4444;
+    }
+
+    .shimmer {
+        opacity: 0.6;
+    }
 </style>
 
 @code {
@@ -56,7 +72,10 @@
         _isChecking = true;
         StateHasChanged();
 
-        var res = await Mediator.Send(new VerifyGroundednessCommand(Answer, Context));
+        var authState = await AuthProvider.GetAuthenticationStateAsync();
+        var tenantId = authState.User.FindFirst("TenantId")?.Value ?? "global";
+
+        var res = await Mediator.Send(new VerifyGroundednessCommand(Answer, Context, tenantId));
         if (res.IsSuccess)
         {
             _result = res.Value;