Add ZIP-based user data download endpoint, enable AES-256 server-side S3 encryption for all stored documents and audiobooks. Rewrite privacy policy with detailed CCPA categories, service provider disclosures (Vercel/Neon/Railway), and user rights sections. Replace privacy modal with checkbox agreement flow.
- 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`.
