Replace the device-bound Telethon .session file and local CSV folders with
Redis-backed storage so the tool runs on any device from just .env.
- StringSession persisted at <prefix>:session:<phone> (no re-login per device)
- each group export saved as one self-contained JSON key per run:
<prefix>:run:<phone>:<yyyymmddhhmmss>:<group_id>
- REDIS_PREFIX namespaces all keys; applied via a single key() helper
- no cross-key references: deleting any key cannot corrupt another's state
- list_exports() lists history, tolerant of deleted/corrupt keys
tiennm99