Replace manual generate_version.dart script with a custom build_runner
builder that automatically generates lib/version.g.dart from pubspec.yaml
during the build process. This eliminates manual steps and ensures version
info stays in sync.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
