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/ModManager.tsx

@@ -121,6 +121,7 @@ export function ModManager() {
   } | null>(null);
   const [confirmRemove, setConfirmRemove] = useState<string | null>(null);
   const [confirmRestore, setConfirmRestore] = useState<string | null>(null);
+  const [confirmDeleteSnap, setConfirmDeleteSnap] = useState<string | null>(null);
   const debounceRef = useRef<ReturnType<typeof setTimeout>>(null);
 
   // Installed mods
@@ -340,7 +341,7 @@ export function ModManager() {
   };
 
   return (
-    <div className="space-y-6">
+    <div className="space-y-4 sm:space-y-6">
       {/* ── Mod Manager Card ──────────────────────────────── */}
       <Card>
         <CardHeader>
@@ -799,7 +800,7 @@ export function ModManager() {
                           disabled={isBusy}
                           className="text-xs h-9"
                         >
-                          Confirm
+                          Confirm Restore
                         </Button>
                         <Button
                           size="sm"
@@ -810,6 +811,29 @@ export function ModManager() {
                           Cancel
                         </Button>
                       </>
+                    ) : confirmDeleteSnap === snap.dirName ? (
+                      <>
+                        <Button
+                          size="sm"
+                          variant="destructive"
+                          onClick={() => {
+                            deleteSnap.mutate(snap.dirName);
+                            setConfirmDeleteSnap(null);
+                          }}
+                          disabled={isBusy}
+                          className="text-xs h-9"
+                        >
+                          Confirm Delete
+                        </Button>
+                        <Button
+                          size="sm"
+                          variant="ghost"
+                          onClick={() => setConfirmDeleteSnap(null)}
+                          className="text-xs h-9"
+                        >
+                          Cancel
+                        </Button>
+                      </>
                     ) : (
                       <>
                         <Button
@@ -824,7 +848,7 @@ export function ModManager() {
                         <Button
                           size="sm"
                           variant="ghost"
-                          onClick={() => deleteSnap.mutate(snap.dirName)}
+                          onClick={() => setConfirmDeleteSnap(snap.dirName)}
                           disabled={isBusy}
                           className="text-xs h-9 text-muted-foreground sm:opacity-0 sm:group-hover:opacity-100 transition"
                         >