build(admin): track the SPA build output so git deploys carry it

assets/admin/build was gitignored, so servers deployed by git pull kept
running a stale admin bundle — the icon picker integration in the tabbar
and floating-button settings pages never reached them. Track the build
directory (rebuild with: cd assets/admin && npm run build) and commit the
current bundle containing the universal icon picker.

assets/admin/build/ToolsHealth.css

@@ -0,0 +1 @@
+.aksrt-health-grid[data-v-b6c15d59]{display:grid;grid-template-columns:repeat(auto-fit,minmax(240px,1fr));gap:16px}