fix(workspace): keep a bullet's height when clicking into it

The focused textarea was inline-block and left room for descenders below
it, so the row grew by 6 px and everything below shifted on every click.

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

frontend/src/features/workspace/OutlinerBlock.tsx

@@ -1437,6 +1437,8 @@ export const OutlinerBlock: React.FC<OutlinerBlockProps> = ({
               )}
             </div>
 
+            {/* Display block: inline, the focused field would sit on a text baseline and leave a gap below
+                it, so the row grew by a few pixels on every click */}
             <textarea
               ref={(el) => {
                 textareaRef.current = el;
@@ -1482,7 +1484,7 @@ export const OutlinerBlock: React.FC<OutlinerBlockProps> = ({
                   }
                 }
               }}
-              className={`w-full min-h-[1.5rem] resize-none overflow-hidden bg-transparent border-0 focus:outline-none focus:ring-0 leading-relaxed whitespace-pre-wrap break-words [overflow-wrap:anywhere] ${
+              className={`block w-full min-h-[1.5rem] resize-none overflow-hidden bg-transparent border-0 focus:outline-none focus:ring-0 leading-relaxed whitespace-pre-wrap break-words [overflow-wrap:anywhere] ${
                 activeFocus ? 'relative z-0 text-main' : 'absolute inset-0 text-transparent selection:text-transparent pointer-events-none'
               } ${
                 block.type === 'h1'