Shipped a support page with tiered Stripe Checkout

Added a Buy Me a Coffee page to the site. Five preset tiers plus a custom amount field. Each one hits a single API route that creates a Stripe Checkout Session and redirects. No embedded payment form here — donations are simple enough that a redirect to Stripe hosted page makes more sense than embedding Elements. The tiers are just a data array, the component maps over them, and the API route validates the amount and creates the session. Custom amounts are capped because at some point you should probably just email me directly.