chore: add initial BatchTransferFraction contract and corresponding tests

Author: tnkshuuhei

Diff for: src/BatchTransferFraction.sol

@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.28;
+
+import "./interfaces/IHypercertToken.sol";
+
+contract BatchTransferFraction {
+    IHypercertToken public hypercertToken;
+
+    error INVALID_LENGTHS();
+    error INVALID_RECIPIENT(address recipient);
+    error INVALID_TOKEN_ID(uint256 tokenID);
+    error INVALID_CALLER(address caller);
+    error INVALID_HYPERCERT_ADDRESS(address hypercertAddress);
+
+    constructor(address _hypercertToken) {
+        require(_hypercertToken != address(0), INVALID_HYPERCERT_ADDRESS(_hypercertToken));
+        hypercertToken = IHypercertToken(_hypercertToken);
+    }
+}

Diff for: test/BatchTransferFraction.t.sol

@@ -0,0 +1,46 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.28;
+
+import "forge-std/Test.sol";
+import "forge-std/console.sol";
+
+import { BatchTransferFraction } from "../src/BatchTransferFraction.sol";
+import { IHypercertToken } from "../src/interfaces/IHypercertToken.sol";
+
+contract BatchTransferFractionTest is Test {
+    BatchTransferFraction public batchTransferFraction;
+    IHypercertToken public hypercertToken;
+    address public currentPrankee;
+
+    function setUp() public {
+        configureChain();
+        batchTransferFraction = new BatchTransferFraction(address(hypercertToken));
+    }
+
+    function testDeployment() public view {
+        assertNotEq(address(batchTransferFraction), address(0));
+    }
+
+    function configureChain() public {
+        if (block.chainid == 10) {
+            // Optimism mainnet
+            hypercertToken = IHypercertToken(0x822F17A9A5EeCFd66dBAFf7946a8071C265D1d07);
+        } else if (block.chainid == 11_155_111) {
+            // Sepolia
+            hypercertToken = IHypercertToken(0xa16DFb32Eb140a6f3F2AC68f41dAd8c7e83C4941);
+        } else {
+            revert("Unsupported chain");
+        }
+    }
+
+    modifier prankception(address prankee) {
+        address prankBefore = currentPrankee;
+        vm.stopPrank();
+        vm.startPrank(prankee);
+        _;
+        vm.stopPrank();
+        if (prankBefore != address(0)) {
+            vm.startPrank(prankBefore);
+        }
+    }
+}