Enhancement: add Mollie as a payment provider option in the builder (next to Polar.sh)

[BuckwheatMoustache]

Summary

Add Mollie as a selectable payment provider in the stack builder (better-t-stack.dev/new), alongside the existing Polar.sh option.

Motivation

The builder currently offers Polar.sh as a payments choice. Mollie is a widely-used, European-headquartered payment service provider with strong EU coverage and a broad set of local payment methods (iDEAL, Bancontact, SEPA, credit cards, Apple Pay, and more). Offering it next to Polar.sh would give teams - especially those building for European markets or with EU data-residency requirements - a first-class, batteries-included alternative without hand-rolling the integration.

Proposal

• Add a mollie option to the payments selector in the web builder, positioned next to polar.sh.
• Scaffold the equivalent integration wiring the project already provides for Polar (SDK dependency, environment variables, and a minimal example/handler) so a generated project works out of the box.
• Mollie ships an official Node SDK (@mollie/api-client) and documented webhooks, so the integration shape should mirror the existing Polar provider closely.

Alternatives

Users can integrate Mollie manually today, but a built-in option keeps parity with the existing Polar.sh experience and lowers setup friction.

Happy to help and/or open a PR if this is something the maintainers would welcome. Thanks for the great tool!

[hiSandog]

A small acceptance checklist would make this easier to review: configuration shape, default behavior, migration or backward compatibility, and at least one test that exercises Enhancement: add Mollie as a payment provider option in the builder (next to Polar.sh). mollie is a useful concrete anchor because it is named directly in the report.