Volume was mounting ./backend to /workspaces/backend, but devcontainer.json
pointed VS Code to /workspaces/familienarchiv — causing the broken path shown
in Remote Explorer.
Now mounts the full project root to /workspaces/familienarchiv, which matches
the workspaceFolder variable. Also gives container access to frontend/ for
running npm run generate:api without leaving the devcontainer.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>