test: achieve 80%+ branch/function coverage on frontend logic (E2E-03)

515 tests across 38 files. Branch coverage 88%, function coverage 83%
on testable logic (stores, composables, api, utils, services, router).

New test files: websocket, useLoginSounds, useMobileBackButton,
useControllerNav, routes. Extended: rpc-client (99.5%), container store
(100%). Fixed: useNavSounds AudioContext mock, type errors across tests.

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

neode-ui/vitest.config.ts

@@ -14,5 +14,22 @@ export default defineConfig({
     globals: true,
     root: '.',
     passWithNoTests: true,
+    exclude: ['e2e/**', 'node_modules/**'],
+    coverage: {
+      provider: 'v8',
+      reporter: ['text', 'text-summary'],
+      include: [
+        'src/api/*.ts',
+        'src/stores/*.ts',
+        'src/composables/*.ts',
+        'src/utils/*.ts',
+        'src/services/*.ts',
+        'src/router/*.ts',
+      ],
+      exclude: ['src/**/__tests__/**', 'src/**/*.d.ts', 'src/main.ts'],
+      thresholds: {
+        branches: 80,
+      },
+    },
   }
 })