- add `launcher_token` to launcher config API/schema and save/load flow
- update dashboard token resolution order: env var -> launcher config -> random
- expose token source in startup logs and auth help metadata (including config path)
- add launcher token input to the config page and wire frontend form/API updates
- update login help/i18n copy and extend backend tests for new token-source behavior
- centralize gateway log level resolution and normalization
- propagate debug flags to spawned launcher and gateway processes
- add a log level selector to the logs page
- cover the new behavior with backend and config tests
wenjie