feat(workspace): bar above the phone keyboard to indent, outdent and move bullets

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

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

@@ -1,5 +1,5 @@
 import { describe, it, expect } from 'vitest';
-import { listLabel, numberedLabels } from '../outlineList';
+import { listLabel, moveSibling, numberedLabels } from '../outlineList';
 import type { DocumentBlock } from '../types';
 
 const blk = (id: string, level: number, type: DocumentBlock['type'] = 'numbered'): DocumentBlock => ({
@@ -25,3 +25,33 @@ describe('numbered lists', () => {
     });
   });
 });
+
+describe('moveSibling (phone bar ↑ ↓)', () => {
+  // A
+  //   a1
+  //   a2
+  //     a2x
+  // B
+  //   b1
+  // C
+  const tree = [blk('A', 0), blk('a1', 1), blk('a2', 1), blk('a2x', 2), blk('B', 0), blk('b1', 1), blk('C', 0)];
+  const ids = (bs: DocumentBlock[]) => bs.map((b) => b.id).join(' ');
+
+  it('swaps with the previous sibling and takes the children along', () => {
+    expect(ids(moveSibling(tree, 'B', -1))).toBe('B b1 A a1 a2 a2x C');
+    expect(ids(moveSibling(tree, 'a2', -1))).toBe('A a2 a2x a1 B b1 C');
+  });
+
+  it('swaps with the next sibling, jumping over its whole branch', () => {
+    expect(ids(moveSibling(tree, 'A', 1))).toBe('B b1 A a1 a2 a2x C');
+    expect(ids(moveSibling(tree, 'a1', 1))).toBe('A a2 a2x a1 B b1 C');
+  });
+
+  it('never leaves its parent and stops at the ends', () => {
+    expect(moveSibling(tree, 'a1', -1)).toBe(tree); // first child
+    expect(moveSibling(tree, 'a2', 1)).toBe(tree); // last child
+    expect(moveSibling(tree, 'A', -1)).toBe(tree);
+    expect(moveSibling(tree, 'C', 1)).toBe(tree);
+    expect(moveSibling(tree, 'missing', 1)).toBe(tree);
+  });
+});