feat: add 7702 compitable semi modular account

src/account/SemiModularAccount7702.sol

@@ -0,0 +1,37 @@
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity ^0.8.26;
+
+import {IModularAccount} from "@erc6900/reference-implementation/interfaces/IModularAccount.sol";
+import {IEntryPoint} from "@eth-infinitism/account-abstraction/interfaces/IEntryPoint.sol";
+
+import {SemiModularAccountBase} from "./SemiModularAccountBase.sol";
+
+/// @title Semi-Modular Account for EIP-7702 EOAs
+/// @author Alchemy
+/// @notice An implementation of a semi-modular account which reads the signer as the address(this).
+/// @dev Inherits SemiModularAccountBase. This account can be used as the delegate contract of an EOA with
+/// EIP-7702, where address(this) (aka the EOA address) is the default fallback signer.
+contract SemiModularAccount7702 is SemiModularAccountBase {
+    constructor(IEntryPoint anEntryPoint) SemiModularAccountBase(anEntryPoint) {}
+
+    /// @inheritdoc IModularAccount
+    function accountId() external pure override returns (string memory) {
+        return "alchemy.sma-7702.1.0.0";
+    }
+
+    /// @dev If the fallback signer is set in storage, means the fallback signer has been updated. We ignore the
+    /// address(this) EOA signer.
+    function _retrieveFallbackSignerUnchecked(SemiModularAccountStorage storage _storage)
+        internal
+        view
+        override
+        returns (address)
+    {
+        address storageFallbackSigner = _storage.fallbackSigner;
+        if (storageFallbackSigner != address(0)) {
+            return storageFallbackSigner;
+        }
+
+        return address(this);
+    }
+}