Polish remaining UX items: avatar fallback, chat truncation, delete confirmations

- PlayerAvatar component with onError fallback to initial badge; used in
  PlayerManager and ChatBridge.
- ChatBridge: truncate long usernames to 16 chars with tooltip, add avatar
  column, bump tinted text colors to -300 for better dark-mode contrast.
- BackupManager: confirm step for Delete (was one-click).
- ModManager: confirm step for snapshot Delete, clearer "Confirm Restore" /
  "Confirm Delete" labels, unify outer spacing with the rest of admin.

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

components/BackupManager.tsx

@@ -21,6 +21,7 @@ type Backup = {
 export function BackupManager() {
   const queryClient = useQueryClient();
   const [confirmRestore, setConfirmRestore] = useState<string | null>(null);
+  const [confirmDelete, setConfirmDelete] = useState<string | null>(null);
   const [result, setResult] = useState<{ ok: boolean; message: string } | null>(null);
 
   const { data: backups = [] } = useQuery<Backup[]>({
@@ -151,6 +152,29 @@ export function BackupManager() {
                         Cancel
                       </Button>
                     </>
+                  ) : confirmDelete === b.name ? (
+                    <>
+                      <Button
+                        size="sm"
+                        variant="destructive"
+                        onClick={() => {
+                          deleteBackup.mutate(b.name);
+                          setConfirmDelete(null);
+                        }}
+                        disabled={isBusy}
+                        className="text-xs h-9"
+                      >
+                        Confirm Delete
+                      </Button>
+                      <Button
+                        size="sm"
+                        variant="ghost"
+                        onClick={() => setConfirmDelete(null)}
+                        className="text-xs h-9"
+                      >
+                        Cancel
+                      </Button>
+                    </>
                   ) : (
                     <>
                       <a
@@ -173,7 +197,7 @@ export function BackupManager() {
                       <Button
                         size="sm"
                         variant="ghost"
-                        onClick={() => deleteBackup.mutate(b.name)}
+                        onClick={() => setConfirmDelete(b.name)}
                         disabled={isBusy}
                         className="text-xs h-9 text-muted-foreground sm:opacity-0 sm:group-hover:opacity-100 transition"
                       >