refactor(ext/sw): extract storage.ts + move itemToManifestEntry (Plan C Phase 2)

P1.9: loadDeviceSettings / loadBlacklist / saveBlacklist / saveDeviceSettings
+ itemToManifestEntry were duplicated across popup-only.ts and
content-callable.ts. Lifts the four storage helpers into service-worker/
storage.ts and itemToManifestEntry into service-worker/vault.ts.

Both router files now import from one home each. Adds storage.test.ts
covering round-trips and defaults.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

extension/src/service-worker/__tests__/storage.test.ts

@@ -0,0 +1,56 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+import { loadDeviceSettings, saveDeviceSettings, loadBlacklist, saveBlacklist }
+  from '../storage';
+
+function mockChromeStorage(initial: Record<string, unknown> = {}) {
+  const store: Record<string, unknown> = { ...initial };
+  (global as { chrome: unknown }).chrome = {
+    storage: {
+      local: {
+        get: vi.fn((keys: string | string[]) => {
+          const arr = Array.isArray(keys) ? keys : [keys];
+          const out: Record<string, unknown> = {};
+          for (const k of arr) if (k in store) out[k] = store[k];
+          return Promise.resolve(out);
+        }),
+        set: vi.fn((kv: Record<string, unknown>) => {
+          Object.assign(store, kv);
+          return Promise.resolve();
+        }),
+      },
+    },
+  } as never;
+  return store;
+}
+
+describe('service-worker/storage', () => {
+  beforeEach(() => { mockChromeStorage(); });
+
+  it('loadDeviceSettings returns default when storage is empty', async () => {
+    const s = await loadDeviceSettings();
+    expect(s.captureEnabled).toBe(false);
+    expect(s.captureStyle).toBe('bar');
+  });
+
+  it('loadDeviceSettings returns stored value', async () => {
+    mockChromeStorage({ relicarioSettings: { captureEnabled: true, captureStyle: 'toast' } });
+    const s = await loadDeviceSettings();
+    expect(s.captureEnabled).toBe(true);
+    expect(s.captureStyle).toBe('toast');
+  });
+
+  it('saveDeviceSettings persists', async () => {
+    const store = mockChromeStorage();
+    await saveDeviceSettings({ captureEnabled: true, captureStyle: 'bar' });
+    expect(store.relicarioSettings).toEqual({ captureEnabled: true, captureStyle: 'bar' });
+  });
+
+  it('loadBlacklist returns empty array by default', async () => {
+    expect(await loadBlacklist()).toEqual([]);
+  });
+
+  it('saveBlacklist / loadBlacklist round-trips', async () => {
+    await saveBlacklist(['example.com', 'evil.test']);
+    expect(await loadBlacklist()).toEqual(['example.com', 'evil.test']);
+  });
+});