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.
Switch tts_segments schema to use settings_json (jsonb for Postgres, text for SQLite)
instead of settings_hash. Update related indexes and migration SQL. Regenerate
Drizzle snapshots to reflect the new structure. This improves flexibility for
storing TTS settings and enables more robust segment lookups.
