Improve test script portability

- Replace #!/bin/bash with #!/usr/bin/env bash for better portability
- This helps ensure scripts run correctly on different systems where bash
  might be located in different paths

🤖 Generated with [Claude Code](https://claude.ai/code)

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

test_local.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 set -e
 
 # Detect OS and handle accordingly