GitLab

- Add Distribution section to README.md with Web, iOS, and Android subsections
- Web section covers GitHub Pages/Netlify deploy and WhatsApp sharing, refs SHARE.md
- iOS section: prerequisites table (macOS, Xcode 15+, CocoaPods) + 6-step build guide
- Android section: prerequisites table (Android Studio, JDK 17) + 5-step build guide
- Create CONTRIBUTING.md: file structure, architecture overview, add-variant guide,
  platform config reference, development workflow, and code style notes
- Add _readme documentation keys to capacitor.config.json and manifest.json
  explaining key field purposes (JSON does not support // comments)
- service-worker.js and capacitor-bridge.js retain existing header comments
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>