feat: add account center with subscription management and EVM wallet payment integration.

contracts/PolyWeatherCheckout.sol

@@ -0,0 +1,49 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.24;
+
+interface IERC20 {
+    function transferFrom(address from, address to, uint256 value) external returns (bool);
+}
+
+contract PolyWeatherCheckout {
+    address public owner;
+    address public treasury;
+    address public immutable usdc;
+    mapping(bytes32 => bool) public paidOrder;
+
+    event OrderPaid(
+        bytes32 indexed orderId,
+        address indexed payer,
+        uint256 indexed planId,
+        address token,
+        uint256 amount
+    );
+
+    modifier onlyOwner() {
+        require(msg.sender == owner, "ONLY_OWNER");
+        _;
+    }
+
+    constructor(address _usdc, address _treasury) {
+        require(_usdc != address(0) && _treasury != address(0), "ZERO_ADDR");
+        owner = msg.sender;
+        usdc = _usdc;
+        treasury = _treasury;
+    }
+
+    function setTreasury(address _treasury) external onlyOwner {
+        require(_treasury != address(0), "ZERO_ADDR");
+        treasury = _treasury;
+    }
+
+    function pay(bytes32 orderId, uint256 planId, uint256 amount, address token) external {
+        require(token == usdc, "TOKEN_NOT_ALLOWED");
+        require(amount > 0, "AMOUNT_ZERO");
+        require(!paidOrder[orderId], "ORDER_PAID");
+
+        paidOrder[orderId] = true;
+        require(IERC20(usdc).transferFrom(msg.sender, treasury, amount), "TRANSFER_FAILED");
+
+        emit OrderPaid(orderId, msg.sender, planId, usdc, amount);
+    }
+}