feat(cli): Add Commet as payments option

[decker-dev]

Commet is an all-in-one billing platform designed for startups building SaaS and AI products. As a Merchant of Record, Commet handles:

• Global payments — Accept payments from any country from day one
• Tax compliance — Automatic tax calculation, no need to register in other jurisdictions
• Flexible billing — Subscriptions, usage-based, and seat-based pricing
• Customer portal — Self-service billing management

Commet uses a Plan-First model where you define Plans with Features (boolean, metered, seats) and customers subscribe to those plans.

Proposal

Add commet as a new option for the existing --payments flag.

--payments <provider>: commet, none, ...

Usage

create-better-t-stack my-app --payments commet

Environment Variables

COMMET_API_KEY=
COMMET_WEBHOOK_SECRET=

Dependencies

"@commet/node": "latest"

[linear]

BET-246