feat: add ReportsToPicker for agent management

- Introduced ReportsToPicker component in AgentConfigForm and NewAgent pages to allow selection of an agent's manager.
- Updated organizational structure documentation to reflect the ability to change an agent's manager post-creation.
- Enhanced error handling in ConfigurationTab to provide user feedback on save failures.

ui/src/pages/AgentDetail.tsx

@@ -17,6 +17,7 @@ import { issuesApi } from "../api/issues";
 import { usePanel } from "../context/PanelContext";
 import { useSidebar } from "../context/SidebarContext";
 import { useCompany } from "../context/CompanyContext";
+import { useToast } from "../context/ToastContext";
 import { useDialog } from "../context/DialogContext";
 import { useBreadcrumbs } from "../context/BreadcrumbContext";
 import { queryKeys } from "../lib/queryKeys";
@@ -1356,6 +1357,7 @@ function ConfigurationTab({
   updatePermissions: { mutate: (permissions: AgentPermissionUpdate) => void; isPending: boolean };
 }) {
   const queryClient = useQueryClient();
+  const { pushToast } = useToast();
   const [awaitingRefreshAfterSave, setAwaitingRefreshAfterSave] = useState(false);
   const lastAgentRef = useRef(agent);
 
@@ -1377,9 +1379,17 @@ function ConfigurationTab({
       queryClient.invalidateQueries({ queryKey: queryKeys.agents.detail(agent.id) });
       queryClient.invalidateQueries({ queryKey: queryKeys.agents.detail(agent.urlKey) });
       queryClient.invalidateQueries({ queryKey: queryKeys.agents.configRevisions(agent.id) });
+      queryClient.invalidateQueries({ queryKey: queryKeys.agents.list(agent.companyId) });
     },
-    onError: () => {
+    onError: (err) => {
       setAwaitingRefreshAfterSave(false);
+      const message =
+        err instanceof ApiError
+          ? err.message
+          : err instanceof Error
+            ? err.message
+            : "Could not save agent";
+      pushToast({ title: "Save failed", body: message, tone: "error" });
     },
   });