feat: select text across bullets and delete it like a text editor; Ctrl+Z in tasks; notes and lists without emoji; custom done columns complete tasks

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

frontend/src/features/workspace/MergeDialog.tsx

@@ -93,7 +93,7 @@ export const MergeDialog: React.FC<MergeDialogProps> = ({ docs, sourceId, target
                   onClick={() => setTarget(d.id)}
                   className="w-full min-h-[44px] sm:min-h-0 px-3 py-2 flex items-center gap-2 text-left text-xs text-main hover:bg-panel-elevated"
                 >
-                  <span className="shrink-0">{d.icon || '🗒️'}</span>
+                  {d.icon && <span className="shrink-0">{d.icon}</span>}
                   <span className="truncate flex-1">{d.title || 'Unbenannte Notiz'}</span>
                   {d.folderPath && <span className="text-[10px] text-faint truncate max-w-[40%]">{d.folderPath}</span>}
                 </button>