vis.js requires a pixel-sized container — flex:1 is ignored.
Use position:fixed toolbar + JS-measured height for the graph div,
stored as window._network for resize handling.
next server restart.
Admin page now shows:
- Overall disk bar (used/free/%)
- Per-user table: total, activities (with file count), originals (with Strava breakdown), merged, images
- A mini bar per user showing relative size
- Red ⚠ warning if orphaned temp ZIPs are still present for a user
- Delete activities button (reloads sizes after)