fix: replace import.meta.dirname with Node 20-compatible fileURLToPath

import.meta.dirname was added in Node 21.2.0 and is not available on
Node 20.x. Replace with the standard dirname(fileURLToPath(import.meta.url))
pattern so CI passes on both 20.x and 22.x matrix entries.

https://claude.ai/code/session_01EXcoDfR7Hvoobx8aNBdE67

Author: claude

packages/claude-code/test/init.test.ts

@@ -2,9 +2,10 @@ import { describe, it, expect } from "vitest";
 import { spawnSync, type SpawnSyncReturns } from "node:child_process";
 import { mkdtempSync, readFileSync, mkdirSync, writeFileSync, rmSync } from "node:fs";
 import { tmpdir } from "node:os";
-import { join, resolve } from "node:path";
+import { join, resolve, dirname } from "node:path";
+import { fileURLToPath } from "node:url";
 
-const BIN = resolve(import.meta.dirname, "../bin/init.js");
+const BIN = resolve(dirname(fileURLToPath(import.meta.url)), "../bin/init.js");
 
 function run(args: string[], env?: Record<string, string>): SpawnSyncReturns<string> {
   return spawnSync(process.execPath, [BIN, ...args], {