test(offline): add reviewer-requested coverage for offline-sync core logic

Adds the unit tests called out in the PR #120 review (test-coverage
aspect). No production logic changes — the only non-test edit is exporting
the already-injectable warmInfiniteAll helper so it can be unit tested.

Server (Jest):
- persistence.extension.spec.ts: onStoreDocument classification matrix
  (no-op / title-only / body+title / body-only), onLoadDocument seed +
  persist gating (early-return, page-null, ydoc seed, already-seeded
  no-persist, legacy content->ydoc), and seedTitleFragment 4-branch guard.
- collaboration.util.spec.ts: buildTitleSeedYdoc round-trip.
- environment.service.spec.ts: getCorsAllowedOrigins / isSwaggerEnabled.
- auth.controller.spec.ts: login returnToken opt-in branch.

Client (Vitest):
- query-persister.test.ts: shouldDehydrateOfflineQuery status + allowlist
  gates and OFFLINE_PERSIST_ROOTS membership.
- is-capacitor.test.ts: isCapacitorNativePlatform platform detection.
- make-offline.test.ts: warmInfiniteAll cursor walk / maxPages / error
  swallow, and warmPageYdoc settle-once + timeout + teardown.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

apps/server/src/integrations/environment/environment.service.spec.ts

@@ -5,6 +5,13 @@ import { EnvironmentService } from './environment.service';
 describe('EnvironmentService', () => {
   let service: EnvironmentService;
 
+  // Build a service over a stub ConfigService whose get(key, def) returns
+  // values from the supplied env map (falling back to the provided default).
+  const makeService = (env: Record<string, string>) =>
+    new EnvironmentService({
+      get: (k: string, d?: string) => (k in env ? env[k] : d),
+    } as any);
+
   beforeEach(() => {
     service = new EnvironmentService(
       {} as any, // configService
@@ -14,4 +21,50 @@ describe('EnvironmentService', () => {
   it('should be defined', () => {
     expect(service).toBeDefined();
   });
+
+  describe('getCorsAllowedOrigins', () => {
+    it('splits, trims, and drops empty entries', () => {
+      const svc = makeService({
+        CORS_ALLOWED_ORIGINS:
+          'https://a.com, https://b.com ,, https://c.com',
+      });
+      expect(svc.getCorsAllowedOrigins()).toEqual([
+        'https://a.com',
+        'https://b.com',
+        'https://c.com',
+      ]);
+    });
+
+    it('returns an empty array when the var is absent', () => {
+      const svc = makeService({});
+      expect(svc.getCorsAllowedOrigins()).toEqual([]);
+    });
+  });
+
+  describe('isSwaggerEnabled', () => {
+    it('is true for "true"', () => {
+      expect(makeService({ SWAGGER_ENABLED: 'true' }).isSwaggerEnabled()).toBe(
+        true,
+      );
+    });
+
+    it('is true case-insensitively for "TRUE"', () => {
+      expect(makeService({ SWAGGER_ENABLED: 'TRUE' }).isSwaggerEnabled()).toBe(
+        true,
+      );
+    });
+
+    it('defaults to false when absent', () => {
+      expect(makeService({}).isSwaggerEnabled()).toBe(false);
+    });
+
+    it('is false for non-"true" values', () => {
+      expect(makeService({ SWAGGER_ENABLED: '0' }).isSwaggerEnabled()).toBe(
+        false,
+      );
+      expect(makeService({ SWAGGER_ENABLED: 'yes' }).isSwaggerEnabled()).toBe(
+        false,
+      );
+    });
+  });
 });