feat(cli): add -V/--version flag to print package version

[trick77]

Summary

• Adds -V and --version flags to the CLI
• Reads the version from package.json at runtime and prints it as v<version>
• Exits with code 0 after printing

Test plan

• Run opencode-presets -V and verify output matches package.json version
• Run opencode-presets --version and verify same output