fix: textarea fills full editor height when content is short

autoHeight() now uses Math.max(contentH, wrapH-48) so textarea fills available space even with short content, and grows beyond when content is long.

frontend/editor-poc.html

@@ -1063,10 +1063,13 @@ body { font-family: var(--sans); background: var(--bg); color: var(--text); heig
     autoHeight();
   });
 
-  // ---- Auto-height textarea ----
+  // ---- Auto-height textarea (fill available space, grow beyond) ----
   function autoHeight() {
     ta.style.height = 'auto';
-    ta.style.height = ta.scrollHeight + 'px';
+    var contentH = ta.scrollHeight;
+    // Minimum: fill the editor-wrap's visible area minus padding
+    var wrapH = editorWrap.clientHeight - 48;
+    ta.style.height = Math.max(contentH, wrapH) + 'px';
   }
   ta.addEventListener('mouseup', function() { setTimeout(showBubble, 50); });
   // Bubble follows cursor on any selection change (keyboard too)