#61 API: Terminate All User Sessions

Implement endpoint to terminate all sessions for a user. Endpoint: DELETE /api/v1/users/{user_id}/sessions Query Parameters: - exclude_current: Exclude current session (default: true) Response: Count of terminated sessions Required Permissions: tenant_admin, or self Implementation Requirements: - Invalidate all JWTs for user - Option to exclude current session - Bulk operation efficiency - Log bulk termination in audit - Force password reset option Use Cases: - Security incident response - Employee offboarding - Compromised account recovery With ultra attention to details and correctness. Before closing: write comment summarizing implementation with screenshot.