fix: Optimizer.sol base class only guards slots 0 and 1 (#968)

Replace the two per-slot require checks with a loop over all 8 input slots
so future subclasses using slots 2-7 are protected from silent uint256 wrap.
Add testCalculateParamsRevertsOnNegativeMantissaSlots2to7 to verify the guard.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

onchain/src/Optimizer.sol

@@ -370,8 +370,9 @@ contract Optimizer is Initializable, UUPSUpgradeable, IOptimizer {
         returns (uint256 capitalInefficiency, uint256 anchorShare, uint24 anchorWidth, uint256 discoveryDepth)
     {
         // Guard against negative mantissa — uint256() cast silently wraps negatives.
-        require(inputs[0].mantissa >= 0, "negative mantissa");
-        require(inputs[1].mantissa >= 0, "negative mantissa");
+        for (uint256 k; k < 8; k++) {
+            require(inputs[k].mantissa >= 0, "negative mantissa");
+        }
         // Extract slots 0 and 1 (shift=0 assumed — mantissa IS the value)
         uint256 percentageStaked = uint256(inputs[0].mantissa);
         uint256 averageTaxRate = uint256(inputs[1].mantissa);

onchain/test/Optimizer.t.sol

@@ -347,6 +347,18 @@ contract OptimizerTest is Test {
         optimizer.calculateParams(inputs);
     }
 
+    /**
+     * @notice calculateParams reverts when any of inputs[2..7].mantissa is negative
+     */
+    function testCalculateParamsRevertsOnNegativeMantissaSlots2to7() public {
+        for (uint256 k = 2; k < 8; k++) {
+            OptimizerInput[8] memory inputs;
+            inputs[k] = OptimizerInput({mantissa: -1, shift: 0});
+            vm.expectRevert("negative mantissa");
+            optimizer.calculateParams(inputs);
+        }
+    }
+
     /**
      * @notice Non-admin calling upgradeTo should revert with UnauthorizedAccount
      */