fix: avoid stray zero in consultation composer

tests/unit/coding-teacher-ui.test.tsx

@@ -96,6 +96,15 @@ async function ready() {
   await waitFor(() => expect(streams.has('first')).toBe(true));
 }
 describe('teacher side chat', () => {
+  it('does not render a zero for an empty legacy friend draft', async () => {
+    localStorage.setItem('makelore-consultation-draft:signed-out:p:friend', JSON.stringify({ text: '', references: [] }));
+    render(<TeacherChatPanel projectId="p" sourceId="c" />);
+    await ready();
+    const composer = screen.getByLabelText('向智能体提问').closest('form');
+    expect(composer).not.toHaveTextContent(/^0/);
+    expect(screen.queryByText('查看旧版朋友草稿')).not.toBeInTheDocument();
+  });
+
   it('retains failed input and retries with the same request id, then appends a reply only on click', async () => {
     const bringBack = vi.fn();
     api.send