docs: sync roadmap with actual implementation status

- Update roadmap to reflect completed features (LSP, JetBrains plugin, etc.)
- Remove all timeline references (dates, quarters)
- Add VersionBadge component for automatic version display
- Add version.json for centralized version management
- Restructure milestones to match t-ruby compiler (Milestone 1-7)
- Sync all languages (en, ko, ja)

Author: yhk1038