Adds a manual backup button on each project card (next to Start/Reset
when stopped, and next to Files when running) that saves a gzipped
tarball of the container's /workspace to a host path via the native save
dialog.
Backend: download_container_backup runs `tar czf -` inside the container
(so excludes + compression happen there rather than streaming a 16 GB
workspace) and pipes stdout straight to the chosen file. Regenerable
build artifacts (node_modules, target, .git/objects) are excluded so the
archive stays restore-sized. Returns bytes written; stderr is captured
for error reporting and a zero-byte result is treated as failure.
Works whether the container is running or stopped (only requires that it
exists). Verified on the Ubuntu/GNU-tar container base.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
shadow-test
d07dcdfea9