- Reorganized utility modules from `src/utils` to `src/lib` for clearer separation of concerns.
- Introduced new, dedicated type definitions in `src/types` for improved type safety in configuration and TTS API interactions.
- Replaced `src/types/appConfig.ts` with `src/types/config.ts`.
- Added `src/types/tts.ts` for TTS request payloads, error structures, and retry options.
- Updated module imports across several contexts (`Config`, `EPUB`, `HTML`, `PDF`, `TTS`) and components to reflect the new `lib` and `types` locations.
- Enhanced TTS API request and error handling in `src/app/api/tts/route.ts` and TTS-consuming contexts with explicit types.
- Simplified `ProgressCard`, `ProgressPopup`, and `AudiobookExportModal` components by removing the `isProcessing` prop, centralizing processing state management.
- Streamlined `HTMLContext` by removing `createFullAudioBook` and `isAudioCombining` properties, focusing its scope.
- Reduce Playwright worker allocation from 75% to 50% for better resource management
- Disable parallel test execution temporarily to isolate flaky test behavior
- Enhance audio utility to fail fast on user cancellation, preventing unnecessary retries
- Consolidate test-specific utilities within individual test suites for better isolation
- Introduce export functionality test coverage with new export.spec.ts suite
