feat: add send_usd example for ton (#37)

* add send_usd example for ton

* update data

* update readme

* address comments

price_feeds/ton/send_usd/.env.sample

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+WALLET_VERSION="v4"
+WALLET_MNEMONIC=""
+TONCENTER_API_KEY="" # Get from https://toncenter.com/
+PYTH_CONTRACT_ADDRESS="EQB4ZnrI5qsP_IUJgVJNwEGKLzZWsQOFhiaqDbD7pTt_f9oU" 
+SEND_USD_CONTRACT_ADDRESS="EQBSXhaZHDbb7WRcdxXnmlFXsh_VDLJFSuFdWWV_FxxWFx-q"

price_feeds/ton/send_usd/.gitignore

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+node_modules
+temp
+build
+dist
+.DS_Store
+
+# VS Code
+.vscode/*
+.history/
+*.vsix
+
+# IDEA files
+.idea
+
+# VIM
+Session.vim

price_feeds/ton/send_usd/.prettierignore

@@ -0,0 +1 @@
+build

price_feeds/ton/send_usd/.prettierrc

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+{
+    "printWidth": 120,
+    "tabWidth": 4,
+    "singleQuote": true,
+    "bracketSpacing": true,
+    "semi": true
+}

price_feeds/ton/send_usd/README.md

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+# send_usd
+
+This repository contains examples of applications integrating Pyth products and services.	Sample contract demonstrating Pyth price feed integration on TON.
+
+## Overview
+
+This contract enables USD-denominated payments on TON by integrating with Pyth price oracles. It supports two operations:
+
+1. `send_usd` - Send a USD-denominated payment that gets converted to TON at current price
+
+Message format:
+
+```typescript
+{
+    queryId: number,     // 64-bit unique identifier for the request
+    recipient: Address,  // TON address of payment recipient
+    usdAmount: number,  // Amount in USD dollars
+    updateData: Buffer, // Pyth price update data (converted to cell chain)
+    value: bigint      // Amount of TON to attach to message
+}
+```
+
+The `updateData` field contains Pyth price feed data and must be obtained from [Hermes](https://hermes.pyth.network/docs/). This data is converted to a TON cell chain format using the `createCellChain()` helper from the [pyth-ton-js](https://www.npmjs.com/package/@pythnetwork/pyth-ton-js) library. The Pyth contract can be found [here](https://github.com/pyth-network/pyth-crosschain/tree/main/target_chains/ton/contracts).
+
+2. Pyth price update callback
+
+-   Receives price updates from Pyth oracle contract
+-   Automatically processes pending USD payments using latest price
+
+## Setup
+
+1.  Copy environment config:
+
+```bash
+cp .env.example .env
+```
+
+2.  Configure `.env`:
+
+```
+WALLET_MNEMONIC="your mnemonic here"
+```
+
+## Usage
+
+1.  Deploy contract:
+
+```bash
+npx blueprint run deploySendUsd --custom https://testnet.toncenter.com/api/v2/jsonRPC --custom-version v2 --custom-type testnet --custom-key <YOUR-API-KEY> --mnemonic
+```
+
+This will deploy the contract and update `.env` with the deployed address.
+
+2. Send USD payment:
+
+```bash
+npx blueprint run sendUsdPayment <YOUR-TON-WALLET-ADDRESS> 1 --custom https://testnet.toncenter.com/api/v2/jsonRPC --custom-version v2 --custom-type testnet --custom-key <YOUR-API-KEY> --mnemonic
+```
+
+## Project structure
+
+-   `contracts` - Smart contract source code and dependencies
+-   `wrappers` - Contract wrapper classes implementing serialization and compilation
+-   `tests` - Contract test suite
+-   `scripts` - Deployment and interaction scripts
+
+## Development
+
+### Build
+
+`npx blueprint build` or `yarn blueprint build`
+
+### Test
+
+`npx blueprint test` or `yarn blueprint test`
+
+### Deploy or run scripts
+
+`npx blueprint run` or `yarn blueprint run`
+
+### Create new contract
+
+`npx blueprint create ContractName` or `yarn blueprint create ContractName`