fix(web): code review pass — scroll watch, SSE same-origin, store concurrency, modal reset, admin validation

web/src/api/client.ts

@@ -75,3 +75,15 @@ export async function request<T>(path: string, opts: RequestOptions = {}): Promi
     clearTimeout(timer)
   }
 }
+
+// buildQuery 把任意对象拼成 "?k=v&..." 形式；undefined / null / '' 跳过；
+// 数组与对象用 String() 退化（业务侧目前没有数组 query 需求）。
+export function buildQuery(params: object): string {
+  const q = new URLSearchParams()
+  for (const [k, v] of Object.entries(params)) {
+    if (v === undefined || v === null || v === '') continue
+    q.set(k, String(v))
+  }
+  const s = q.toString()
+  return s ? '?' + s : ''
+}