fix(17): resolve post-merge wave 2 integration issues

- SettingsSheet: void the navigate('/login') promise (react-router v7 returns Promise) — eslint no-floating-promises
- InstructionSheet.test: wrap SettingsSheet render in MemoryRouter — 17-05 added useNavigate() which needs Router context

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

apps/pwa/src/components/InstructionSheet.test.tsx

@@ -10,6 +10,7 @@
 import React from 'react';
 import { describe, it, expect, vi, beforeEach } from 'vitest';
 import { render, screen, fireEvent } from '@testing-library/react';
+import { MemoryRouter } from 'react-router';
 import { QueryClient, QueryClientProvider } from '@tanstack/react-query';
 
 // ── Module mocks ──────────────────────────────────────────────────────────────
@@ -70,7 +71,11 @@ function renderWithQueryClient(ui: React.ReactElement) {
   const queryClient = new QueryClient({
     defaultOptions: { queries: { retry: false }, mutations: { retry: false } },
   });
-  return render(<QueryClientProvider client={queryClient}>{ui}</QueryClientProvider>);
+  return render(
+    <QueryClientProvider client={queryClient}>
+      <MemoryRouter>{ui}</MemoryRouter>
+    </QueryClientProvider>,
+  );
 }
 
 // ── Tests ─────────────────────────────────────────────────────────────────────

apps/pwa/src/components/SettingsSheet.tsx

@@ -142,7 +142,7 @@ export function SettingsSheet({ isOpen, onClose }: SettingsSheetProps) {
       // API failure does not block navigation — server cookie was cleared or already expired
     }
     onClose();
-    navigate('/login');
+    void navigate('/login');
   };
 
   const handleToggle = async () => {