Introduce SegmentsSidebar component and supporting reader UI for segment-level
navigation and inspection. Add TTS segments manifest and clear API endpoints to
enable efficient retrieval and management of segment variants. Update TTS
segment schema to include settings_hash for improved lookup and indexing,
and adjust indexes to use settings_hash instead of settings_json. Update
contexts and types to support segment variant display and interaction.
This enhances document navigation and TTS segment management for end users.
- Introduce `USE_ANONYMOUS_AUTH_SESSIONS` to make guest access an opt-in feature.
- Transition root-level pages into `(app)` and `(public)` route groups for improved access control.
- Adopt Figtree as the primary typeface and implement a pre-render theme initialization script.
- Decouple audiobook chapter processing into a standalone API route and harden resource ownership logic.
- Replace the legacy footer with a unified layout and add skeleton loading states for document lists.
- Update environment documentation and test suites to align with the revised routing and auth flows.
BREAKING CHANGE: The audiobook generation API has been restructured, moving specific chapter logic to `/api/audiobook/chapter`.
