feat(web): auto-logout on 401 inside apiFetch

Dynamic import breaks the apiFetch <-> auth/store cycle. silent:true
prevents re-POSTing /logout against an already-dead session.

web/src/lib/api/client.test.ts

@@ -79,3 +79,24 @@ describe('api.get/post/del', () => {
     expect(result).toBeNull();
   });
 });
+
+describe('apiFetch 401 interceptor', () => {
+  test('401 response triggers auth.logout({silent:true}) and still throws', async () => {
+    const logoutSpy = vi.fn();
+    vi.doMock('$lib/auth/store.svelte', () => ({
+      logout: logoutSpy,
+      login: vi.fn(),
+      bootstrap: vi.fn(),
+      user: { value: null }
+    }));
+    // Re-import to pick up the mock.
+    const { apiFetch: apiFetchFresh } = await import('./client');
+    stubFetch(401, { error: { code: 'unauthorized', message: 'session expired' } });
+    await expect(apiFetchFresh('/api/me')).rejects.toMatchObject({
+      code: 'unauthorized',
+      status: 401
+    });
+    expect(logoutSpy).toHaveBeenCalledWith({ silent: true });
+    vi.doUnmock('$lib/auth/store.svelte');
+  });
+});

web/src/lib/api/client.ts

@@ -23,6 +23,13 @@ export async function apiFetch(path: string, init?: RequestInit): Promise<unknow
   });
   const body = res.status === 204 ? null : await res.json().catch(() => null);
   if (!res.ok) {
+    if (res.status === 401) {
+      // Lazy import: auth/store imports from this file, so a top-level
+      // import would be circular. By the time any 401 actually happens
+      // at runtime, both modules have finished loading.
+      const { logout } = await import('$lib/auth/store.svelte');
+      await logout({ silent: true });
+    }
     const envelope = body && (body as { error?: { code?: string; message?: string } }).error;
     const err: ApiError = {
       code: envelope?.code ?? 'unknown',