When sessions.write_json_snapshots is disabled, Hermes only writes to
state.db (SQLite). loadHermesSession now falls back to reading from
~/.hermes/state.db when the JSON file is missing.
- Add getHermesDbPath() and loadHermesSessionFromDb() functions
- Use bun:sqlite with readonly mode, try-catch for graceful errors
- JSON file still takes priority (fast path)
- Filter messages to user/assistant/tool roles
- Convert unix timestamps to ISO 8601 strings