- Remove ListSessions and RevokeSession RPC endpoints
- Remove Session message and SessionsSetting from UserSetting
- Remove ACCESS_TOKENS key and AccessTokensSetting
- Update references to use RefreshTokensUserSetting with its own ClientInfo
- Remove UserSessionsSection frontend component
- Clean up user store to remove session and access token settings
- Regenerate protobuf files

The system now uses:
- REFRESH_TOKENS for session management with sliding expiration
- PERSONAL_ACCESS_TOKENS for long-lived API tokens