feat: implement KarmaTiers

This commit introduces a new contract `KarmaTiers` that allows for
maintaing tiers for gasless transactions.

The owner of the contract can add tiers, update tiers and deactivate or
activate them.

Tier names can only be 32 bytes long and there's no overlap allowed
between min and max Karma bounds of the tiers.

Closes #216

script/DeployKarmaTiers.s.sol

@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.26;
+
+import { BaseScript } from "./Base.s.sol";
+import { DeploymentConfig } from "./DeploymentConfig.s.sol";
+
+import { KarmaTiers } from "../src/KarmaTiers.sol";
+
+contract DeployKarmaTiersScript is BaseScript {
+    function run() public returns (KarmaTiers, DeploymentConfig) {
+        DeploymentConfig deploymentConfig = new DeploymentConfig(broadcaster);
+        (address deployer,) = deploymentConfig.activeNetworkConfig();
+
+        vm.startBroadcast(deployer);
+
+        KarmaTiers karmaTiers = new KarmaTiers();
+
+        vm.stopBroadcast();
+
+        return (karmaTiers, deploymentConfig);
+    }
+}