feat(tests): replace nock with MSW mock server infrastructure

Migrate all unit tests from nock-based HTTP interception to a proper
MSW (Mock Service Worker) mock server using msw/node + @mswjs/interceptors.

Changes:
- Add msw@2 as devDependency, remove nock
- Create tests/mocks/server.ts: MSW server with documentation on adding handlers
- Update tests/setup.js: start/stop/reset MSW server in beforeAll/afterEach/afterAll
- Port all 7 nock-based test files to per-test server.use() handlers:
  entities, auth, functions, connectors, integrations, custom-integrations, client
- Replace vi.stubGlobal("fetch", ...) in functions.test.ts with MSW handlers
- Add request capture pattern for asserting headers (Authorization, Base44-State)
- Use RegExp patterns for MSW handlers where operationId contains URL-unsafe chars

All 116 unit tests pass (npm run test:unit exits 0).

Goal: https://github.com/base44-dev/gremlins/issues/873

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

Author: Goal Champion #873

package-lock.json

@@ -40,7 +40,7 @@
     "dotenv": "^16.3.1",
     "eslint": "^9.39.2",
     "eslint-plugin-import": "^2.32.0",
-    "nock": "^13.4.0",
+    "msw": "^2.12.11",
     "typedoc": "^0.28.14",
     "typedoc-plugin-markdown": "^4.9.0",
     "typescript": "^5.3.2",

package.json

@@ -0,0 +1,47 @@
+/**
+ * MSW (Mock Service Worker) server for unit tests.
+ *
+ * ## How to add new handlers
+ *
+ * Call `server.use()` inside a test to register per-test handlers.
+ * They are automatically removed after each test by the global `afterEach`
+ * in `tests/setup.js` (via `server.resetHandlers()`).
+ *
+ * ```ts
+ * import { http, HttpResponse } from 'msw';
+ * import { server } from '../mocks/server';
+ *
+ * test('my test', async () => {
+ *   server.use(
+ *     http.get('https://api.base44.com/api/apps/test-app-id/entities/Todo', () =>
+ *       HttpResponse.json([{ id: '1', title: 'Test' }])
+ *     )
+ *   );
+ *   // ... test code
+ * });
+ * ```
+ *
+ * ## Architecture
+ *
+ * ```
+ * Vitest test → SDK (axios / fetch) → MSW Node server → handler → fake response
+ * ```
+ *
+ * MSW intercepts requests at the Node.js http layer (`@mswjs/interceptors`)
+ * and also intercepts native `fetch` calls. No axios mocking or `vi.stubGlobal`
+ * needed.
+ *
+ * ## Modules and their base URL patterns
+ *
+ * | Module       | Base path                                                        |
+ * |--------------|------------------------------------------------------------------|
+ * | entities     | `/api/apps/:appId/entities/:entityName`                          |
+ * | auth         | `/api/apps/:appId/entities/User/me`, `/api/apps/:appId/auth/...` |
+ * | functions    | `/api/apps/:appId/functions/:name`, `/api/functions/:name`       |
+ * | integrations | `/api/apps/:appId/integration-endpoints/:pkg/:endpoint`          |
+ * | custom-int   | `/api/apps/:appId/integrations/custom/:slug/:operationId`        |
+ * | connectors   | `/api/apps/:appId/external-auth/tokens/:type`                    |
+ */
+import { setupServer } from 'msw/node';
+
+export const server = setupServer();

tests/mocks/server.ts

@@ -1,7 +1,8 @@
 // Load environment variables from .env file
 import dotenv from 'dotenv';
 import './utils/circular-json-handler.js';
-import { beforeAll, afterAll, test } from 'vitest';
+import { beforeAll, afterAll, afterEach } from 'vitest';
+import { server } from './mocks/server.ts';
 
 try {
   dotenv.config({ path: './tests/.env' });
@@ -16,13 +17,18 @@ try {
   console.warn('Failed to load circular JSON handler:', err.message);
 }
 
-// Global beforeAll and afterAll hooks
+// MSW server lifecycle
 beforeAll(() => {
+  server.listen({ onUnhandledRequest: 'warn' });
   console.log('Starting Base44 SDK tests...');
-  // Add any global setup here
+});
+
+afterEach(() => {
+  // Remove per-test handlers registered via server.use()
+  server.resetHandlers();
 });
 
 afterAll(() => {
+  server.close();
   console.log('Completed Base44 SDK tests');
-  // Add any global teardown here
-}); 
+});