feat: add React Router (Remix) framework adapter

[czaydev]

What and why

Closes #96

Adds better-payment/react-router. toReactRouterHandler(source) returns a loader (GET) and an action (POST) for a splat resource route, so React Router v7 and Remix v2 apps mount the handler in one line:

// app/routes/api.pay.$.ts
import { toReactRouterHandler } from 'better-payment/react-router';
export const { loader, action } = toReactRouterHandler(getBetterPayment);

It wraps toFetchHandler and uses a structural { request: Request } type, so there is no dependency on react-router.

• Subpath registered in tsup, package.json exports, vitest and tsconfig.examples.json aliases, size budget (1 kB; built size 0.25 kB gzip)
• Added to the shared scenarios in tests/unit/adapters/adapters.test.ts (lazy source, GET through loader, POST through action)
• Example in examples/frameworks.ts, docs section in English and Turkish (frameworks page, handler table, README), changeset

Checklist

• pnpm lint, pnpm typecheck and pnpm test pass
• Tests cover the change (and forged/invalid input for callbacks and signatures)
• A changeset is included for user-facing changes (pnpm changeset)
• Docs are updated in English and Turkish (node apps/web/scripts/check-translations.mjs), or no docs change is needed
• New user-facing features include a <Since version="x.y.z" /> badge in their docs, or no badge is needed
• No credentials, card numbers or personal data in code, tests, fixtures or logs

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Project	Deployment	Actions	Updated
better-payment-web-xhgb	Ready	Preview	Oct 7, 2026 4:21am UTC

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