fix(auto): add context reset option for scheduled runs

[alexk-dev]

Summary

• add a persisted clearContextBeforeRun flag to scheduler entries and expose it through the dashboard scheduler API
• add a scheduler form toggle and schedule-list badge so Goals & Tasks flows can opt into clearing the session transcript before each scheduled run
• clear the target session messages immediately before auto execution when the flag is enabled, and cover the new behavior with controller, service, and scheduler tests

[sonarqubecloud]

Quality Gate passed

Issues
2 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud