refactor: return slashId for instant slasher

Author: 0xClandestine

src/interfaces/IInstantSlasher.sol

@@ -12,14 +12,16 @@ interface IInstantSlasher is ISlasher {
     /// @notice Immediately executes a slashing request
     /// @param params Parameters defining the slashing request including operator and amount
     /// @dev Can only be called by the authorized slasher
+    /// @return slashId The ID of the slashing request
     function fulfillSlashingRequest(
         IAllocationManager.SlashingParams memory params
-    ) external;
+    ) external returns (uint256 slashId);
 
     /// @notice Immediately executes a slashing request and burns or redistributes shares
     /// @param params Parameters defining the slashing request including operator and amount
     /// @dev Can only be called by the authorized slasher
+    /// @return slashId The ID of the slashing request
     function fulfillSlashingRequestAndBurnOrRedistribute(
         IAllocationManager.SlashingParams memory params
-    ) external;
+    ) external returns (uint256 slashId);
 }

src/slashers/InstantSlasher.sol

@@ -23,14 +23,14 @@ contract InstantSlasher is IInstantSlasher, SlasherBase {
     /// @inheritdoc IInstantSlasher
     function fulfillSlashingRequest(
         IAllocationManager.SlashingParams calldata params
-    ) external virtual override(IInstantSlasher) onlySlasher {
-        _fulfillSlashingRequest(params);
+    ) external virtual override(IInstantSlasher) onlySlasher returns (uint256 slashId) {
+        slashId = _fulfillSlashingRequest(params);
     }
 
     /// @inheritdoc IInstantSlasher
     function fulfillSlashingRequestAndBurnOrRedistribute(
         IAllocationManager.SlashingParams calldata params
-    ) external virtual override onlySlasher {
-        _fulfillSlashingRequestAndBurnOrRedistribute(params);
+    ) external virtual override onlySlasher returns (uint256 slashId) {
+        slashId = _fulfillSlashingRequestAndBurnOrRedistribute(params);
     }
 }