## Problem solved
Short description of the bug fixed or feature added
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## PR-Codex overview
This PR adds `onPurchaseSuccess` callback to various components and hooks in the codebase, triggering when a user completes a purchase using thirdweb pay.
### Detailed summary
- Added `onPurchaseSuccess` callback to `PayEmbed`, `ConnectButton`, `TransactionButton`, and `useSendTransaction`
- Updated props in multiple components to include `onSuccess` callback parameter
- Added type definitions for `BuyWithCryptoStatus` and `BuyWithFiatStatus`
- Implemented logic to call `onSuccess` callback upon successful purchase completion
> The following files were skipped due to too many changes: `packages/thirdweb/src/react/web/ui/ConnectWallet/screens/Buy/fiat/FiatFlow.tsx`
> ✨ Ask PR-Codex anything about this PR by commenting with `/codex {your question}`
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