Add Arbiscan API key configuration to environment and Hardhat setup

Author: Le-Caignec

packages/smart-contract/.env.template

@@ -9,3 +9,6 @@ RPC_URL=
 
 ## Mnemonic for the network
 MNEMONIC=
+
+## Arbiscan API key to verify contracts
+ARBISCAN_API_KEY=

packages/smart-contract/config/env.ts

@@ -24,6 +24,9 @@ const envSchema = z.object({
 
     // Mnemonic de déploiement ou interaction réseau
     MNEMONIC: z.string().min(1, 'MNEMONIC cannot be empty').optional().or(z.literal('')),
+
+    // Clé API pour Arbiscan
+    ARBISCAN_API_KEY: z.string().optional().or(z.literal('')),
 });
 
 export const env = envSchema.parse(process.env);

packages/smart-contract/hardhat.config.ts

@@ -58,7 +58,9 @@ const config: HardhatUserConfig = {
     //to verify contract on Blockscout
     etherscan: {
         apiKey: {
-            bellecour: 'abc',
+            bellecour: 'nothing', // a non-empty string is needed by the plugin.
+            avalancheFujiTestnet: 'nothing', // a non-empty string is needed by the plugin.
+            arbitrumSepolia: env.ARBISCAN_API_KEY,
         },
         customChains: [
             {