fix: validate network before fetch loop for fail-fast behavior

Move network validation before the contract iteration loop so invalid
network strings are caught immediately instead of surfacing during
the first fetch — which is confusing when fetching multiple contracts.

Closes #12

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

Author: satoshai-dev

src/commands/fetch.ts

@@ -1,6 +1,7 @@
 import { defineCommand } from 'citty';
 import { parseContractId, fetchContractAbi } from '../fetcher.js';
 import { generateTypescript, generateJson, defaultFilename } from '../codegen.js';
+import { resolveNetwork } from '../network.js';
 import { writeFile } from 'node:fs/promises';
 import { resolve } from 'node:path';
 
@@ -44,6 +45,9 @@ export const fetchCommand = defineCommand({
       throw new Error(`Invalid format "${format}". Use "ts" or "json".`);
     }
 
+    // Validate network early to fail fast before fetching any contracts
+    resolveNetwork(args.network);
+
     const contractIds = args.contract.split(',').map((s) => s.trim());
 
     for (const contractId of contractIds) {