Adds a server-rendered collapsible file tree section to the overlay
detail page so users can verify what their script/workshop overlays
produced and pull individual artifacts (VPKs, configs) without SSH.
HTMX-driven lazy folder expansion with click-to-download via send_file;
symlinks land anywhere under LEFT4ME_ROOT (so workshop addons stream
from the shared cache) but escapes are refused. Same access rule as the
rest of the page (admin or owner). 39 new tests; full web suite green.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
