cdf22214fa
${workspaceFolder} as the EDH workspace collides with the dev window (VS
Code one-folder-one-window), so plain F5 still landed folderless — now with
the stub warning instead of 'command not found'. The EDH opens
sandbox/ (committed playground with a guided playground.md) instead; its
.threads/ churn is gitignored; README updated.
Fixes #8.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>