Process all scheduled launches that are due for execution.

This endpoint is designed to be called by Cloud Scheduler periodically (e.g., every 5 minutes). It finds all launches with:

• status IN ['pending', 'scheduled']
• scheduled_for <= now

And executes them via the LaunchOrchestrator.

Authentication: This endpoint should be protected by Cloud Scheduler's OIDC authentication at the infrastructure level, not by user authentication.

Returns:

• processed: number of launches executed
• results: list of {launch_id, status, error?}