feat(web): add /settings page with ListenBrainz section

Adds api.put helper, ListenBrainz API module with query/mutation
helpers, a /settings route with token + enable/disable UI, and 5
tests. Adds Settings to the Shell nav.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web/src/routes/settings/settings.test.ts

@@ -0,0 +1,102 @@
+import { afterEach, describe, expect, test, vi } from 'vitest';
+import { render, screen, fireEvent, waitFor } from '@testing-library/svelte';
+import { readable, writable } from 'svelte/store';
+import type { LBStatus } from '$lib/api/listenbrainz';
+
+vi.mock('$lib/api/listenbrainz', () => ({
+  createLBStatusQuery: vi.fn(),
+  createTokenMutation: vi.fn(),
+  createEnabledMutation: vi.fn(),
+  setListenBrainzToken: vi.fn(),
+  setListenBrainzEnabled: vi.fn()
+}));
+
+vi.mock('@tanstack/svelte-query', async (orig) => {
+  const actual = (await orig()) as Record<string, unknown>;
+  return {
+    ...actual,
+    useQueryClient: () => ({ invalidateQueries: vi.fn() })
+  };
+});
+
+import SettingsPage from './+page.svelte';
+import {
+  createLBStatusQuery,
+  createTokenMutation,
+  createEnabledMutation,
+  setListenBrainzToken,
+  setListenBrainzEnabled
+} from '$lib/api/listenbrainz';
+
+function mockStatusStore(data: LBStatus) {
+  return readable({ data, isPending: false, isError: false });
+}
+
+function mockMutationStore(mutateFn: (vars: unknown) => void = vi.fn()) {
+  return readable({ isPending: false, mutate: mutateFn, mutateAsync: vi.fn() });
+}
+
+afterEach(() => vi.clearAllMocks());
+
+describe('Settings page — ListenBrainz', () => {
+  test('token-not-set state renders input + Save button', async () => {
+    (createLBStatusQuery as ReturnType<typeof vi.fn>).mockReturnValue(
+      mockStatusStore({ enabled: false, token_set: false, last_scrobbled_at: null })
+    );
+    (createTokenMutation as ReturnType<typeof vi.fn>).mockReturnValue(mockMutationStore());
+    (createEnabledMutation as ReturnType<typeof vi.fn>).mockReturnValue(mockMutationStore());
+    render(SettingsPage);
+    await waitFor(() =>
+      expect(screen.getByPlaceholderText(/paste your lb token/i)).toBeInTheDocument()
+    );
+    expect(screen.getByRole('button', { name: /save/i })).toBeInTheDocument();
+  });
+
+  test('token-set state renders masked + Clear button', async () => {
+    (createLBStatusQuery as ReturnType<typeof vi.fn>).mockReturnValue(
+      mockStatusStore({ enabled: false, token_set: true, last_scrobbled_at: null })
+    );
+    (createTokenMutation as ReturnType<typeof vi.fn>).mockReturnValue(mockMutationStore());
+    (createEnabledMutation as ReturnType<typeof vi.fn>).mockReturnValue(mockMutationStore());
+    render(SettingsPage);
+    await waitFor(() => expect(screen.getByText(/\(set\)/)).toBeInTheDocument());
+    expect(screen.getByText('clear')).toBeInTheDocument();
+  });
+
+  test('Save button calls setListenBrainzToken with typed value', async () => {
+    (createLBStatusQuery as ReturnType<typeof vi.fn>).mockReturnValue(
+      mockStatusStore({ enabled: false, token_set: false, last_scrobbled_at: null })
+    );
+    const mutateFn = vi.fn();
+    (createTokenMutation as ReturnType<typeof vi.fn>).mockReturnValue(mockMutationStore(mutateFn));
+    (createEnabledMutation as ReturnType<typeof vi.fn>).mockReturnValue(mockMutationStore());
+    render(SettingsPage);
+    const input = await screen.findByPlaceholderText(/paste your lb token/i);
+    await fireEvent.input(input, { target: { value: 'mytoken' } });
+    await fireEvent.click(screen.getByRole('button', { name: /save/i }));
+    await waitFor(() => expect(mutateFn).toHaveBeenCalledWith('mytoken', expect.anything()));
+  });
+
+  test('Enabled checkbox is disabled when no token', async () => {
+    (createLBStatusQuery as ReturnType<typeof vi.fn>).mockReturnValue(
+      mockStatusStore({ enabled: false, token_set: false, last_scrobbled_at: null })
+    );
+    (createTokenMutation as ReturnType<typeof vi.fn>).mockReturnValue(mockMutationStore());
+    (createEnabledMutation as ReturnType<typeof vi.fn>).mockReturnValue(mockMutationStore());
+    render(SettingsPage);
+    const checkbox = await screen.findByRole('checkbox');
+    expect(checkbox).toBeDisabled();
+  });
+
+  test('Last-scrobbled-at renders when present', async () => {
+    (createLBStatusQuery as ReturnType<typeof vi.fn>).mockReturnValue(
+      mockStatusStore({ enabled: true, token_set: true, last_scrobbled_at: '2026-04-28T03:00:00Z' })
+    );
+    (createTokenMutation as ReturnType<typeof vi.fn>).mockReturnValue(mockMutationStore());
+    (createEnabledMutation as ReturnType<typeof vi.fn>).mockReturnValue(mockMutationStore());
+    render(SettingsPage);
+    await waitFor(() =>
+      expect(screen.getByText(/last scrobbled:/i)).toBeInTheDocument()
+    );
+  });
+});