refactor(health): add dashboard overview and related drill-down

- Replace health monitor tabs with a dashboard layout
- Add related health drill-down for endpoint, model, and provider cards
- Render provider health as cards and hide empty monitors

apps/aether-gateway/src/control/tests/admin_endpoints.rs

@@ -140,6 +140,25 @@ fn classifies_admin_endpoint_health_providers_as_admin_proxy_route() {
     assert!(!decision.is_execution_runtime_candidate());
 }
 
+#[test]
+fn classifies_admin_endpoint_health_related_as_admin_proxy_route() {
+    let headers = headers(&[]);
+    let uri: Uri = "/api/admin/endpoints/health/related?dimension=model&value=gpt-5"
+        .parse()
+        .expect("uri should parse");
+    let decision =
+        classify_control_route(&http::Method::GET, &uri, &headers).expect("route should classify");
+
+    assert_eq!(decision.route_class.as_deref(), Some("admin_proxy"));
+    assert_eq!(decision.route_family.as_deref(), Some("endpoints_health"));
+    assert_eq!(decision.route_kind.as_deref(), Some("health_related"));
+    assert_eq!(
+        decision.auth_endpoint_signature.as_deref(),
+        Some("admin:endpoints_health")
+    );
+    assert!(!decision.is_execution_runtime_candidate());
+}
+
 #[test]
 fn classifies_admin_endpoint_key_rpm_as_admin_proxy_route() {
     let headers = headers(&[]);