fix: use consistent DEBUG env var check in world-vercel

Change DEBUG=1 check to just DEBUG (truthy) to be consistent with
the debug package pattern used throughout the codebase.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: pranaygp

packages/world-vercel/src/utils.ts

@@ -294,7 +294,7 @@ export async function makeRequest<T>({
           await parseResponseBody(response)
             .then((r) => r.data as { message?: string; code?: string })
             .catch(() => ({}));
-        if (process.env.DEBUG === '1') {
+        if (process.env.DEBUG) {
           const stringifiedHeaders = Array.from(headers.entries())
             .map(([key, value]: [string, string]) => `-H "${key}: ${value}"`)
             .join(' ');