polish(admin): 抽出后台控件包并统一各页布局与交互

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

frontend/components/admin/AdminSearchField.tsx

@@ -0,0 +1,61 @@
+"use client";
+
+import { Search, X } from "lucide-react";
+import type { FormEvent } from "react";
+
+/** 左图标、可清除、Enter 提交；不要再并排「搜索」按钮 */
+export default function AdminSearchField({
+  value,
+  onChange,
+  onSubmit,
+  onClear,
+  placeholder,
+  ariaLabel,
+}: {
+  value: string;
+  onChange: (v: string) => void;
+  onSubmit?: () => void;
+  onClear?: () => void;
+  placeholder?: string;
+  ariaLabel: string;
+}) {
+  const handleSubmit = (e: FormEvent) => {
+    e.preventDefault();
+    onSubmit?.();
+  };
+
+  const clear = () => {
+    onChange("");
+    onClear?.();
+  };
+
+  return (
+    <form onSubmit={handleSubmit} className="relative flex-1 min-w-0" role="search">
+      <Search
+        size={15}
+        className="absolute left-3.5 top-1/2 -translate-y-1/2 pointer-events-none"
+        style={{ color: "var(--ink-3)" }}
+        aria-hidden
+      />
+      <input
+        type="text"
+        value={value}
+        onChange={(e) => onChange(e.target.value)}
+        placeholder={placeholder}
+        aria-label={ariaLabel}
+        className="field pl-10 pr-9 py-2.5"
+      />
+      {value ? (
+        <button
+          type="button"
+          onClick={clear}
+          aria-label="清除搜索"
+          className="absolute right-2.5 top-1/2 -translate-y-1/2 w-6 h-6 inline-flex items-center justify-center rounded-full transition-colors hover:bg-[var(--panel-2)]"
+          style={{ color: "var(--ink-3)" }}
+        >
+          <X size={14} />
+        </button>
+      ) : null}
+    </form>
+  );
+}