Update buffbench to run with base2-free

Author: jahooma

evals/buffbench/main.ts

@@ -8,7 +8,7 @@ async function main() {
   // Use 'external:codex' for OpenAI Codex CLI
   await runBuffBench({
     evalDataPaths: [path.join(__dirname, 'eval-codebuff.json')],
-    agents: ['base2'],
+    agents: ['base2-free'],
     taskConcurrency: 5,
   })