docs: add note about removing daily image builds

refactor: remove daily image build schedule

refactor: remove history persistence feature

Simplify script: use hardcoded fabianlema registry user instead of auto-detection

Fix permissions: create node home directory and pre-create mount points

Remove script auto-update, add daily rebuild schedule for latest opencode

Add auto-update check and persistent history support

Fix zsh compatibility: use array for platform args

Remove load messages from script for silent module loading

Fix platform_flag expansion in docker run command

Change config directory to ~/.config/opencode-sandbox/

Add helper script and README for easy usage

Add GitHub Actions workflow for multi-arch Docker builds

Initial Dockerfile with opencode-ai and dev tools