feat(ui): slim dashboard tile to hostname + online/offline only

Run status, Start/Cancel/View controls, and non-destructive toggle all
live on /hosts/{id} — duplicating them on the dashboard tile clogged
the grid and wouldn't scale past a handful of hosts.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

internal/web/static/app.css

@@ -117,14 +117,8 @@ button.danger:hover { background: rgba(229,100,102,.1); }
   text-decoration: none;
 }
 .tile > *:not(.tile-link) { position: relative; z-index: 1; }
-.tile-primary-action { display: flex; gap: 8px; }
-.tile-primary-action .inline { margin: 0; }
-.tile-primary-action:empty { display: none; }
 .tile-head { display: flex; justify-content: space-between; align-items: center; }
 .tile-name { font-weight: 600; }
-.tile-header-right { display: flex; align-items: center; gap: 10px; }
-.tile-status { font-size: 12px; color: var(--text-dim); text-transform: uppercase; letter-spacing: .5px; }
-.tile-idle .tile-status { color: var(--text-dim); }
 
 .tile-last-seen {
   font-family: var(--mono);