Enhance ComboHandler and orchestrator functionality with access control and error handling improvements

- Added AccessControl to ComboHandler for role-based access management.
- Implemented gas estimation for plan execution and improved gas limit checks.
- Updated execution and preparation methods to enforce step count limits and role restrictions.
- Enhanced error handling in orchestrator API endpoints with AppError for better validation feedback.
- Integrated request timeout middleware for improved request management.
- Updated Swagger documentation to reflect new API structure and parameters.

contracts/test/FuzzTest.t.sol

@@ -0,0 +1,40 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.20;
+
+import "forge-std/Test.sol";
+import "../ComboHandler.sol";
+
+contract FuzzTest is Test {
+    ComboHandler handler;
+
+    function setUp() public {
+        // Setup
+    }
+
+    function testFuzz_PlanExecution(
+        bytes32 planId,
+        bytes calldata signature,
+        address signer
+    ) public {
+        // Fuzz test plan execution with random inputs
+        // Verify no unexpected reverts
+        // Check gas usage stays within bounds
+    }
+
+    function testFuzz_StepValidation(
+        uint8 stepType,
+        uint256 amount,
+        address asset
+    ) public {
+        // Fuzz test step validation
+        // Verify validation logic handles edge cases
+    }
+
+    function testFuzz_GasLimits(uint256 numSteps) public {
+        numSteps = bound(numSteps, 1, 20);
+        
+        // Test gas limits with varying step counts
+        // Verify gas usage is predictable
+    }
+}
+