Document pikpak-kotlin 1.0.0 Getting started, best practices, playback, magnets and instant create, drive operations, uploads and offline tasks, errors and retries, architecture with the 2026-09-27 design review, dated measurements, history of removed designs, and the development and release checklist. Replaces the README's manual, DESIGN-NOTES.md and the DeepWiki page. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_0119qFo3dRwvZArC7NQHigca