fix(auth): allow admins to change any username including their own

apps/web/src/App.test.tsx

@@ -154,6 +154,39 @@ describe('users admin', () => {
     expect(await within(table).findByText('@ilya')).toBeInTheDocument();
   });
 
+  it.each(['root', 'anna'])('lets admins change the username of %s', async (target) => {
+    const root = makeUser('root', 'admin');
+    const anna = makeUser('anna', 'user');
+    const { user, api, session } = await renderApp([root, anna], '/admin/users', { signedInAs: root });
+    await user.click(await screen.findByRole('button', { name: `Действия с ${target}` }));
+    await user.click(screen.getByRole('menuitem', { name: 'Изменить логин' }));
+    const dialog = screen.getByRole('dialog', { name: 'Изменить логин' });
+    const input = within(dialog).getByLabelText('Логин');
+    await user.clear(input);
+    await user.type(input, `new.${target}`);
+    await user.click(within(dialog).getByRole('button', { name: 'Сохранить' }));
+    await waitFor(() => expect(screen.queryByRole('dialog')).not.toBeInTheDocument());
+    expect(await screen.findByText(`@new.${target}`)).toBeInTheDocument();
+    expect(api.users.get(target === 'root' ? root.id : anna.id)?.username).toBe(`new.${target}`);
+    if (target === 'root') expect(session.state).toMatchObject({ status: 'signed_in', user: { username: 'new.root' } });
+  });
+
+  it('keeps the username dialog open when the new username is taken', async () => {
+    const root = makeUser('root', 'admin');
+    const anna = makeUser('anna', 'user');
+    const { user, api } = await renderApp([root, anna], '/admin/users', { signedInAs: root });
+    await user.click(await screen.findByRole('button', { name: 'Действия с anna' }));
+    await user.click(screen.getByRole('menuitem', { name: 'Изменить логин' }));
+    const dialog = screen.getByRole('dialog', { name: 'Изменить логин' });
+    const input = within(dialog).getByLabelText('Логин');
+    await user.clear(input);
+    await user.type(input, 'ROOT');
+    await user.click(within(dialog).getByRole('button', { name: 'Сохранить' }));
+    await waitFor(() => expect(input).toHaveAttribute('aria-invalid', 'true'));
+    expect(api.users.get(anna.id)?.username).toBe('anna');
+    expect(dialog).toBeInTheDocument();
+  });
+
   it('offers moderators only what they may do', async () => {
     const mod = makeUser('mod', 'moderator');
     const anna = makeUser('anna', 'user');