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/pasteOutline.ts

@@ -2,6 +2,7 @@ import type { BlockType } from './types';
 
 // Turns pasted (Markdown) text into outline items: headings, todos, bullets, numbered items, dividers,
 // fenced code and paragraphs. A blank line ends a paragraph; indentation becomes the nesting level.
+// Content below a heading is nested under it (H2 below H1 one level deeper), so sections fold and zoom.
 
 export interface PastedItem {
   type: BlockType;
@@ -31,6 +32,8 @@ export function parsePastedLines(rawLines: string[]): PastedItem[] {
   let current: PastedItem | null = null;
   let inCode = false;
   let afterHeading = false;
+  const headings: { rank: number; level: number }[] = []; // open headings, innermost last
+  const sectionLevel = () => (headings.length ? headings[headings.length - 1].level + 1 : 0);
 
   const flush = () => {
     if (current) {
@@ -52,13 +55,13 @@ export function parsePastedLines(rawLines: string[]): PastedItem[] {
     if (rawLine.trim().startsWith('```')) {
       inCode = true;
       flush();
-      current = { type: 'text', content: rawLine, indent: 0 };
+      current = { type: 'text', content: rawLine, indent: sectionLevel() };
       afterHeading = false;
       continue;
     }
 
     const { width, rest } = leadingWidth(rawLine);
-    const indent = levelOf(width);
+    const indent = sectionLevel() + levelOf(width);
     const line = rest.trimEnd();
 
     // A blank line ends the paragraph or list item
@@ -71,13 +74,18 @@ export function parsePastedLines(rawLines: string[]): PastedItem[] {
     if (heading) {
       flush();
       afterHeading = true;
-      items.push({ type: (['h1', 'h2', 'h3'] as const)[heading[1].length - 1], content: heading[2], indent });
+      const rank = heading[1].length;
+      while (headings.length && headings[headings.length - 1].rank >= rank) headings.pop();
+      const level = sectionLevel();
+      headings.push({ rank, level });
+      items.push({ type: (['h1', 'h2', 'h3'] as const)[rank - 1], content: heading[2], indent: level });
       continue;
     }
     if (/^(?:-{3,}|\*{3,}|_{3,})$/.test(line)) {
       flush();
       afterHeading = false;
-      items.push({ type: 'divider', content: '---', indent });
+      headings.length = 0; // a divider closes the sections
+      items.push({ type: 'divider', content: '---', indent: 0 });
       continue;
     }