The four newest service cards (Security Center, SamiMail, SamiPanel,
Revenue Center) plus Gitea referenced /assets/*.png files that were
never committed, so the dashboard fell back to the walkxcode CDN which
has no icons for these custom services -> blank icons.
Sources: SamiMail/SamiPanel brand packs from Samihost, Gitea from
walkxcode dashboard-icons, DashCaddy logo = copy of dashcaddy-logo-light.
Verified live on DNS2: all 15 cards render icons (img.naturalWidth > 0),
health page shows all four newest Up 100% uptime.