fix(web): exclude lib/__tests__ from Jest runner

Tests in lib/__tests__ use bun:test mock.module() which is not
supported by the Jest stub. These tests should run with bun test only.

This fixes CI failure where ban-conditions.test.ts failed due to
missing fetch polyfill when Stripe SDK was initialized.

Author: brandonkachen

web/jest.config.cjs

@@ -19,6 +19,7 @@ const config = {
   },
   testPathIgnorePatterns: [
     '<rootDir>/src/__tests__/e2e',
+    '<rootDir>/src/lib/__tests__', // Uses bun:test mock.module() - run with bun test
     '<rootDir>/src/app/api/v1/.*/__tests__',
     '<rootDir>/src/app/api/agents/publish/__tests__',
     '<rootDir>/src/app/api/agents/\\[publisherId\\]/.*/__tests__',