Add WeCom markdown alerts and keep target exits while strategy is paused.

Notify open/close/start/pause/fault with SIM vs LIVE venue labels; configure webhook in Settings.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/api/client.ts

@@ -299,6 +299,13 @@ export type RuntimeSettings = {
   sim: boolean;
 };
 
+export type NotifySettings = {
+  enabled: boolean;
+  webhook_configured: boolean;
+  webhook_url_masked: string | null;
+  venue_label: string;
+};
+
 export async function downloadBackup(name: string): Promise<void> {
   await ensureFreshToken();
   const token = getToken();