[Lower priority] App data clear (faster iteration without reinstall)

[thymikee]

Priority: Lower / backlog.

Clear app data (cache, storage, DB) without full reinstall to get a "fresh" app state faster. iOS: e.g. delete app container contents or use simctl; Android: pm clear <package>. Would complement existing reinstall for quicker iteration when the app binary is unchanged.

Acceptance criteria (high level):

• Command to clear app data for session app (or specified app)
• Document difference from reinstall (data clear vs full reinstall)