fix(feedback): theme buttons, badge the Info button, simplify admin actions

- style the About feedback button and the form's Send/attach/remove buttons with
  the accent/border tokens used by the New Game CTA, so they follow light/dark
  theme (the previous .btn/.ghost classes were not defined globally); the attach
  button is a neutral 📎 icon button with an aria-label
- show a round badge on the About 'Feedback' button when a reply is waiting
- admin: one 'ban from feedback' checkbox shared by Delete and Delete-all (via
  button formaction); hide Mark read when already read and Archive when archived
- e2e: match the About button by substring (its name gains the badge)

ui/src/screens/About.svelte

@@ -34,7 +34,9 @@
   <p class="muted">{t('about.version', { v: version })}</p>
 
   {#if !(app.profile?.isGuest ?? true)}
-    <button class="btn feedback" onclick={() => navigate('/feedback')}>{t('feedback.title')}</button>
+    <button class="feedback" onclick={() => navigate('/feedback')}>
+      {t('feedback.title')}{#if app.feedbackReplyUnread}<span class="fbadge">1</span>{/if}
+    </button>
   {/if}
 </div>
 
@@ -78,4 +80,27 @@
     font-size: 0.9rem;
     margin: 0;
   }
+  .feedback {
+    align-self: flex-start;
+    padding: 12px 18px;
+    border: 1px solid var(--accent);
+    background: var(--accent);
+    color: var(--accent-text);
+    border-radius: var(--radius);
+    font-weight: 600;
+  }
+  /* The reply badge sits on the accent button, so it inverts the accent colours. */
+  .fbadge {
+    display: inline-block;
+    margin-left: 8px;
+    min-width: 18px;
+    padding: 0 5px;
+    border-radius: 999px;
+    background: var(--accent-text);
+    color: var(--accent);
+    font-size: 0.78rem;
+    font-weight: 700;
+    line-height: 1.55;
+    text-align: center;
+  }
 </style>