Creates a small executable wrapper for stdio MCP servers.

Hermes' stdio transport reads JSON-RPC from the child's stdout. Many MCP servers also write human-readable logs to stderr.

This module generates a temporary wrapper script that:

• Executes the real server command (passed as the wrapper's first argument)
• Captures the server's stderr to a temp file
• Replays captured stderr only when the server exits non-zero

This keeps successful runs quiet while preserving debugging output for failures.