Introduces src/types.d.ts and test/types.d.ts for Cloudflare Workers and test utilities. Enhances JSDoc comments and type annotations across test files for better type safety and clarity. Updates tsconfig.json to use bundler module resolution and include additional type sources. Minor test logic and assertion improvements for robustness.
Modularizes test helpers into separate files for assertions, generators, and mocks, and updates imports for platform tests. Adds new tests to verify Authorization header forwarding for authenticated requests. Cleans up and simplifies test setup, and updates fixtures for clarity and maintainability.