Add --version flag to vmnet-broker

[nirs]

Summary

Add a --version flag to the vmnet-broker binary to print version information and exit.

Motivation

1. Install verification: The install workflow can verify the correct version is installed
2. User troubleshooting: Users can easily check what version they have
3. Consistency: Matches vmnet-helper's behavior

Implementation

• Check for --version in main() before setup
• Print version info and exit
• Use YAML output like vmnet-helper
• Example output:

  $ /Library/Application\ Support/vmnet-broker/vmnet-broker --version
  version: v0.3.0
  commit: a459afb853e8cb06e0fdb28df3350d4859d6a460
  

Usage in install workflow

out=$("/Library/Application Support/vmnet-broker/vmnet-broker" --version)
version=$(echo $out | jq .version)
commit=$(echo $out | jq .commit)

if [[ "$version" != "$EXPECTED_VERSION" ]]; then
  echo "Version mismatch"
  exit 1
fi

if [[ "$commit" != "$EXPECTED_COMMIT" ]]; then
  echo "Commit mismatch"
  exit 1
fi