feat(workspace): journal panel toggle, view kept across tabs, sections nest under headings

- the journal opens as a framed panel and closes on a second click,
  returning to the previous note; journal state and the last regular note
  survive tab switches, the fallback note is never a journal day
- pasted and imported markdown nests content under its heading (H2 below
  H1), Enter on a heading creates a child, '- ' / '* ' / '+ ' start a bullet

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

frontend/src/features/workspace/OutlinerBlock.tsx

@@ -622,6 +622,10 @@ export const OutlinerBlock: React.FC<OutlinerBlockProps> = ({
         val = val.replace(/^\[[xX]\]\s/, '');
         typeOverride = 'todo';
         checkedOverride = true;
+      } else if (val === '- ' || val === '* ' || val === '+ ') {
+        // Markdown list marker typed into an empty block: it already is a bullet, drop the marker
+        val = '';
+        if (!['text', 'bullet', 'paragraph'].includes(block.type || 'text')) typeOverride = 'bullet';
       } else if ((val === '1. ' || val === '1) ') && block.type !== 'numbered') {
         // "1. " typed into an empty bullet starts a numbered list
         val = '';