Billing: Integrate Polar usage events

[cuevaio]

Description

Send usage records to Polar for billing and subscription management.

Tasks

• From the gateway Lambda, send Polar Events usage records per execution
• Include required fields:
  • Organization ID / user ID
  • Machine type
  • Billed duration (seconds)
  • Price
  • Metadata (input/output size, etc.)
• Implement idempotency for usage events
• Add error handling for Polar API failures
• Implement retry logic with backoff if Polar is down
• Add dead-letter queue or fallback for failed events

Acceptance Criteria

• All executions generate Polar usage events
• Events are idempotent (no duplicate billing)
• System gracefully handles Polar downtime
• Failed events are recoverable