fix(19): resolve post-merge wave-4 harness integration gaps

Two issues surfaced only when plans 19-04 (login UI) and 19-05 (Option C
bypass + login.spec) were merged together and run against the real stack —
neither executor could catch them in isolation:

1. LOCAL_SESSION_SECRET was added to the CI harness (ci.yml) but not to the
   local dev stack (docker-compose.dev.yml). Without it the real-login success
   path (POST /api/auth/local/login) 503s when signing the session cookie, so
   the e2e round-trip failed. Add the same fixed dev-only value to the dev
   compose override (dev-only target; never a production secret).

2. login.spec test 1 assumed clearing the local-session cookie yields a
   logged-out state, but under the always-on DEV_AUTH_BYPASS devAuthBypass()
   injects DEV_USER into /api/me regardless of any cookie — a logged-out state
   is architecturally unreachable in this bypass-only harness. Reframe the test
   to drive /login directly (validating the real-browser render of all brand +
   form surfaces) and move the unauthenticated root->/login redirect-gate
   coverage to a unit test in App.test.tsx where meQuery.isError is controllable.

Result: API 446/446, PWA 265/265 (+2 gate tests), e2e desktop 42 passed / 3
skipped (all login specs green).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/pwa/src/App.test.tsx

@@ -237,6 +237,58 @@ describe('App — setup-status gate', () => {
   });
 });
 
+// Phase 19 (AUTH-LOCAL-15): the unauthenticated → /login redirect gate. This lives
+// here at the unit level because the e2e harness runs DEV_AUTH_BYPASS-only (global-setup
+// refuses a non-bypass DB), and under the always-on bypass /api/me is authed via DEV_USER
+// injection regardless of any cookie — so a logged-out state (meQuery.isError) is
+// architecturally unreachable in the browser harness. The redirect logic is controllable
+// here by rejecting fetchMe.
+describe('App — auth gate (Phase 19)', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+    window.history.pushState({}, '', '/');
+    mockFetchSetupStatus.mockResolvedValue({ setupComplete: true });
+    _mockFetchAuthMode.mockResolvedValue({ localEnabled: true, oidcEnabled: false });
+  });
+
+  it('redirects to /login when fetchMe errors (unauthenticated) and localEnabled', async () => {
+    mockFetchMe.mockRejectedValue(new Error('401 Unauthorized'));
+
+    const queryClient = makeQueryClient();
+    renderApp(queryClient);
+
+    await waitFor(() => {
+      expect(screen.getByTestId('login-page')).toBeInTheDocument();
+    });
+
+    // The authenticated app shell must NOT render for an unauthenticated user.
+    expect(screen.queryByTestId('calendar-shell')).toBeNull();
+    expect(screen.queryByTestId('app-nav')).toBeNull();
+  });
+
+  it('renders the app shell (not /login) when fetchMe succeeds', async () => {
+    mockFetchMe.mockResolvedValue({
+      user: {
+        id: 1,
+        displayName: 'Test User',
+        color: '#4a90d9',
+        isAdmin: false,
+        needsProviderSetup: false,
+        hasLocalCredential: false,
+      },
+    });
+
+    const queryClient = makeQueryClient();
+    renderApp(queryClient);
+
+    await waitFor(() => {
+      expect(screen.getByTestId('calendar-shell')).toBeInTheDocument();
+    });
+
+    expect(screen.queryByTestId('login-page')).toBeNull();
+  });
+});
+
 describe('App — setupStatus and route presence', () => {
   it('App.tsx references setupStatus queryKey', () => {
     // This test verifies the source-level contract via module inspection.