Add mandatory workflow rules (branching, versioning, docs-sync),
introduce CHANGELOG.md and VERSION file, update development
standards and CLAUDE.md accordingly.
Version: 0.1.1
Add CLAUDE.md, development standards, project structure docs,
and domain model skeleton for the Gartenmanager project.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>