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/lib/__tests__/pasteOutline.test.ts

@@ -20,13 +20,27 @@ describe('parsePastedLines', () => {
     ]);
   });
 
-  it('reads headings, todos, bullets and dividers', () => {
-    expect(parse('# Titel\nText danach\n- [x] erledigt\n- Punkt\n---')).toEqual([
+  it('reads headings, todos, bullets and dividers and nests sections under headings', () => {
+    expect(parse('# Titel\nText danach\n- [x] erledigt\n* Punkt\n  + tiefer\n---\nOhne Abschnitt')).toEqual([
       { type: 'h1', content: 'Titel', indent: 0 },
-      { type: 'text', content: 'Text danach', indent: 0 },
-      { type: 'todo', checked: true, content: 'erledigt', indent: 0 },
-      { type: 'text', content: 'Punkt', indent: 0 },
+      { type: 'text', content: 'Text danach', indent: 1 },
+      { type: 'todo', checked: true, content: 'erledigt', indent: 1 },
+      { type: 'text', content: 'Punkt', indent: 1 },
+      { type: 'text', content: 'tiefer', indent: 2 },
       { type: 'divider', content: '---', indent: 0 },
+      { type: 'text', content: 'Ohne Abschnitt', indent: 0 },
+    ]);
+  });
+
+  it('nests H2 below H1 and closes sections at the same rank', () => {
+    expect(parse('# A\n## A1\n1. eins\n## A2\nText\n# B\n- b')).toEqual([
+      { type: 'h1', content: 'A', indent: 0 },
+      { type: 'h2', content: 'A1', indent: 1 },
+      { type: 'numbered', content: 'eins', indent: 2 },
+      { type: 'h2', content: 'A2', indent: 1 },
+      { type: 'text', content: 'Text', indent: 2 },
+      { type: 'h1', content: 'B', indent: 0 },
+      { type: 'text', content: 'b', indent: 1 },
     ]);
   });