feat(#117): agent-count toasts and persistent error toast dismiss

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ui/src/pages/Admin/GroupsTab.tsx

@@ -122,7 +122,7 @@ export default function GroupsTab() {
       setNewName('');
       setNewParent('');
     } catch {
-      toast({ title: 'Failed to create group', variant: 'error' });
+      toast({ title: 'Failed to create group', variant: 'error', duration: 86_400_000 });
     }
   }
 
@@ -138,7 +138,7 @@ export default function GroupsTab() {
       if (selectedId === deleteTarget.id) setSelectedId(null);
       setDeleteTarget(null);
     } catch {
-      toast({ title: 'Failed to delete group', variant: 'error' });
+      toast({ title: 'Failed to delete group', variant: 'error', duration: 86_400_000 });
       setDeleteTarget(null);
     }
   }
@@ -153,7 +153,7 @@ export default function GroupsTab() {
       });
       toast({ title: 'Group renamed', variant: 'success' });
     } catch {
-      toast({ title: 'Failed to rename group', variant: 'error' });
+      toast({ title: 'Failed to rename group', variant: 'error', duration: 86_400_000 });
     }
   }
 
@@ -166,7 +166,7 @@ export default function GroupsTab() {
       });
       toast({ title: 'Member removed', variant: 'success' });
     } catch {
-      toast({ title: 'Failed to remove member', variant: 'error' });
+      toast({ title: 'Failed to remove member', variant: 'error', duration: 86_400_000 });
     }
   }
 
@@ -180,7 +180,7 @@ export default function GroupsTab() {
         });
         toast({ title: 'Member added', variant: 'success' });
       } catch {
-        toast({ title: 'Failed to add member', variant: 'error' });
+        toast({ title: 'Failed to add member', variant: 'error', duration: 86_400_000 });
       }
     }
   }
@@ -195,7 +195,7 @@ export default function GroupsTab() {
         });
         toast({ title: 'Role assigned', variant: 'success' });
       } catch {
-        toast({ title: 'Failed to assign role', variant: 'error' });
+        toast({ title: 'Failed to assign role', variant: 'error', duration: 86_400_000 });
       }
     }
   }
@@ -209,7 +209,7 @@ export default function GroupsTab() {
       });
       toast({ title: 'Role removed', variant: 'success' });
     } catch {
-      toast({ title: 'Failed to remove role', variant: 'error' });
+      toast({ title: 'Failed to remove role', variant: 'error', duration: 86_400_000 });
     }
   }