Fix cli-plan test failing on Windows

os.homedir() on Windows uses USERPROFILE, not HOME. Set both env vars
in the test so the temp dir is respected as the home directory on all
platforms.

tests/cli-plan.test.ts

@@ -11,6 +11,9 @@ function runCli(args: string[], home: string) {
     env: {
       ...process.env,
       HOME: home,
+      USERPROFILE: home, // os.homedir() uses USERPROFILE on Windows
+      HOMEPATH: home,
+      HOMEDRIVE: '',
     },
     encoding: 'utf-8',
   })