feat: add safe miner control foundation

backend/app/frontend/static/app.css

@@ -1722,3 +1722,52 @@ button.map-position:hover {
 @media (prefers-reduced-motion: reduce) {
     .miner-detail-hero *, .disclosure-list * { scroll-behavior: auto; }
 }
+
+.control-capability-grid {
+    display: grid;
+    grid-template-columns: repeat(3, minmax(0, 1fr));
+    gap: 10px;
+    margin: 14px 0;
+}
+
+.control-capability-grid > div {
+    padding: 10px;
+    border: 1px solid var(--line);
+    background: #f7f8fa;
+}
+
+.miner-control-actions,
+.performance-control {
+    display: flex;
+    align-items: end;
+    gap: 10px;
+}
+
+.miner-control-actions {
+    margin: 12px 0;
+}
+
+.performance-control label {
+    display: block;
+    font-size: 12px;
+    font-weight: 700;
+}
+
+.status-callout {
+    margin: 12px 0;
+    padding: 10px;
+    border-left: 4px solid var(--warn);
+    background: #fff8e6;
+}
+
+@media (max-width: 720px) {
+    .control-capability-grid {
+        grid-template-columns: 1fr;
+    }
+
+    .miner-control-actions,
+    .performance-control {
+        align-items: stretch;
+        flex-direction: column;
+    }
+}