Add the gateway and Home Assistant pages, for 0.16.0
Add the documentation Sixteen pages, moved out of docs/ in the main repository. Links carry no .md here, and the images come from raw.githubusercontent.com, because a wiki is a repository of its own. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01W5BG5WPJxYiFBs5mkkAGni