feat(workspace): copy bullets as Markdown, Ctrl+A twice selects the whole note

Ctrl+C over a selection of several bullets now puts Markdown on the
clipboard (lib/outlineMarkdown.ts, the format of the Markdown export:
tab indent, - [ ] to-dos, headings, callouts, fenced code); pasting it
into a note gives the same bullets again. A second Ctrl+A in a bullet
selects the whole note. Copying goes through the browser's copy event,
so it works on plain HTTP too.

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

frontend/src/lib/__tests__/outlineMarkdown.test.ts

@@ -0,0 +1,44 @@
+import { describe, it, expect } from 'vitest';
+import { blocksToMarkdown } from '../outlineMarkdown';
+import { parsePastedLines } from '../pasteOutline';
+import type { DocumentBlock } from '../types';
+
+const b = (type: DocumentBlock['type'], content: string, level = 0, extra: Partial<DocumentBlock> = {}): DocumentBlock => ({
+  id: Math.random().toString(36).slice(2),
+  type,
+  content,
+  level,
+  ...extra,
+});
+
+describe('blocksToMarkdown', () => {
+  it('writes a nested list with to-dos, headings and code', () => {
+    const md = blocksToMarkdown([
+      b('h2', 'Umzug', 0),
+      b('bullet', 'Server', 1),
+      b('todo', 'Backup prüfen', 2, { checked: true }),
+      b('todo', 'DNS umstellen', 2),
+      b('numbered', 'Erstens', 1),
+      b('code', 'docker compose up -d', 1, { lang: 'bash' }),
+    ]);
+    expect(md).toBe(
+      ['## Umzug', '', '- Server', '\t- [x] Backup prüfen', '\t- [ ] DNS umstellen', '1. Erstens', '```bash', 'docker compose up -d', '```'].join('\n')
+    );
+  });
+
+  it('starts a copied branch at the left margin', () => {
+    expect(blocksToMarkdown([b('bullet', 'Ast', 3), b('bullet', 'Kind', 4)])).toBe('- Ast\n\t- Kind');
+  });
+
+  it('pasted back, it gives the same bullets', () => {
+    // 'text' is the plain bullet of a note
+    const blocks = [b('text', 'Eins', 0), b('text', 'Zwei', 1), b('todo', 'Drei', 2, { checked: true }), b('text', 'Vier', 0)];
+    const items = parsePastedLines(blocksToMarkdown(blocks).split('\n'));
+    expect(items.map((i) => [i.type, i.content, i.indent, Boolean(i.checked)])).toEqual([
+      ['text', 'Eins', 0, false],
+      ['text', 'Zwei', 1, false],
+      ['todo', 'Drei', 2, true],
+      ['text', 'Vier', 0, false],
+    ]);
+  });
+});

frontend/src/lib/outlineMarkdown.ts

@@ -0,0 +1,74 @@
+import type { DocumentBlock } from './types';
+
+// Bullets as Markdown, in the format of the server's Markdown export (BlocksToVaultMarkdown): a nested list
+// with one tab per level, "- [ ]" for to-dos, headings, dividers, callouts and fenced code at the top
+// level as block elements. Used for copying bullets; pasting it back (pasteOutline.ts) gives the same
+// structure. Levels count from the shallowest bullet, so a copied branch starts at the left margin.
+export function blocksToMarkdown(blocks: DocumentBlock[]): string {
+  if (blocks.length === 0) return '';
+  const base = Math.min(...blocks.map((b) => Math.max(0, b.level || 0)));
+  const out: string[] = [];
+  // Children of a top-level heading/callout/code/divider become a list one level up; otherwise their
+  // tab indent would turn them into an indented code block
+  let lift = 0;
+  for (const b of blocks) {
+    let lvl = Math.max(0, (b.level || 0) - base);
+    if (lvl === 0) lift = 0;
+    else lvl = Math.max(0, lvl - lift);
+    const indent = '\t'.repeat(lvl);
+    const content = (b.content || '').replace(/\r\n/g, '\n');
+    const oneLine = content.replace(/\n/g, ' ');
+    // Soft line breaks continue the list item, aligned under its text
+    const cont = (prefix: string) => content.replace(/\n/g, `\n${indent}${prefix}`);
+    const hashes = b.type === 'h1' ? '#' : b.type === 'h2' ? '##' : b.type === 'h3' ? '###' : '';
+
+    if ((b.level || 0) - base <= 0) {
+      if (hashes) {
+        out.push('', `${hashes} ${oneLine}`, '');
+        lift = 1;
+        continue;
+      }
+      if (b.type === 'divider') {
+        out.push('', '---', '');
+        lift = 1;
+        continue;
+      }
+      if (b.type === 'callout') {
+        out.push('', `> ${content.replace(/\n/g, '\n> ')}`, '');
+        lift = 1;
+        continue;
+      }
+      if (b.type === 'code') {
+        out.push('', `\`\`\`${b.lang || ''}`, content, '```', '');
+        lift = 1;
+        continue;
+      }
+    }
+    switch (b.type) {
+      case 'code':
+        out.push(`${indent}\`\`\`${b.lang || ''}`, `${indent}${content.replace(/\n/g, `\n${indent}`)}`, `${indent}\`\`\``);
+        break;
+      case 'todo':
+        out.push(`${indent}- [${b.checked ? 'x' : ' '}] ${cont('  ')}`);
+        break;
+      case 'h1':
+      case 'h2':
+      case 'h3':
+        out.push(`${indent}- ${hashes} ${oneLine}`);
+        break;
+      case 'divider':
+        out.push(`${indent}- ---`);
+        break;
+      case 'callout':
+        out.push(`${indent}- > ${cont('  > ')}`);
+        break;
+      case 'numbered':
+        out.push(`${indent}1. ${cont('   ')}`);
+        break;
+      default:
+        out.push(content.trim() === '' ? `${indent}-` : `${indent}- ${cont('  ')}`);
+    }
+  }
+  // No blank lines at the start and end, at most one in a row
+  return out.join('\n').replace(/\n{3,}/g, '\n\n').replace(/^\n+|\n+$/g, '');
+}