- Add document preview caching logic with in-memory and persisted storage.
- Implement S3 blobstore functions for managing document previews.
- Create rendering functions for PDF and EPUB cover images to JPEG format.
- Introduce database schema and functions for managing document preview metadata.
- Add unit tests for rendering PDF and EPUB previews.
Replaces local filesystem document storage with S3-compatible object storage.
Adds embedded SeaweedFS 'weed mini' for local development and Docker deployments.
Updates document upload flow to use presigned URLs with a server fallback proxy.
Refactors auth configuration to use BASE_URL and AUTH_SECRET.
BREAKING CHANGE: Renamed BETTER_AUTH_URL to BASE_URL and BETTER_AUTH_SECRET to AUTH_SECRET. Removed legacy document upload/content endpoints. Requires S3 environment variables (auto-configured for embedded SeaweedFS).
- Introduce `/api/whisper` endpoint which uses `whisper.cpp` (via a `WHISPER_CPP_BIN` executable) and `ffmpeg` to generate word-level audio alignments from provided audio and text.
- Integrate word-level alignments into `TTSContext`, tracking the currently spoken word based on audio seek position and provided timestamps. Alignments are cached in-memory and fetched asynchronously.
- Add new configuration options (`pdfWordHighlightEnabled`, `epubWordHighlightEnabled`) to `ConfigContext` and `Dexie` for enabling/disabling the feature.
- Implement visual word highlighting in both `PDFViewer` and `EPUBViewer` by mapping TTS-aligned words to rendered text elements.
- Enhance `EPUBContext` and `PDFContext` with new `highlightWordIndex` and `clearWordHighlights` functions, utilizing fuzzy string matching (`cmpstr`) to robustly align spoken words with displayed text for accurate highlighting.
- Update `DocumentSettings` to include user-facing toggles for the new highlighting modes.
- 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.
