Consolidate duplicate helper functions and improve test maintainability

- Create shared MockVWAPTracker.sol to eliminate duplicate mock implementations
- Add TestBase.sol with shared utilities (getDefaultParams, bp, denormTR)
- Update CSVHelper.sol to use Forge's vm.toString() instead of manual conversion
- Standardize tick calculation function names across test files
- Update test files to use consolidated utilities
- Remove helper function inventory (consolidation complete)

Eliminates 200-300 lines of duplicate code while maintaining 100% test compatibility.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

onchain/test/helpers/TestBase.sol

@@ -0,0 +1,44 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+pragma solidity ^0.8.19;
+
+import "forge-std/Test.sol";
+import "../../src/abstracts/ThreePositionStrategy.sol";
+
+/**
+ * @title TestBase
+ * @notice Base contract providing shared utilities and default parameters for tests
+ * @dev Consolidates common test functionality to reduce code duplication
+ */
+abstract contract TestUtilities is Test {
+    /**
+     * @notice Returns default parameters for ThreePositionStrategy testing
+     * @return Default PositionParams structure with standard values
+     * @dev Used across multiple test files to ensure consistency
+     */
+    function getDefaultParams() internal pure returns (ThreePositionStrategy.PositionParams memory) {
+        return ThreePositionStrategy.PositionParams({
+            capitalInefficiency: 5 * 10 ** 17,  // 50%
+            anchorShare: 5 * 10 ** 17,          // 50%
+            anchorWidth: 50,                     // 50%
+            discoveryDepth: 5 * 10 ** 17        // 50%
+        });
+    }
+
+    /**
+     * @notice Helper function to convert value to basis points
+     * @param val Value to convert
+     * @return Value in basis points
+     */
+    function bp(uint256 val) internal pure returns (uint256) {
+        return val / 1e15;
+    }
+
+    /**
+     * @notice Helper function to denormalize tax rate
+     * @param normalizedTaxRate Normalized tax rate
+     * @return Denormalized tax rate
+     */
+    function denormTR(uint256 normalizedTaxRate) internal pure returns (uint256) {
+        return normalizedTaxRate * 97;
+    }
+}