fix(HEL-233): 去掉系统管理按钮属性多余引号，恢复点击

五个无值 data-system-* 属性名后多写了引号，选择器匹配失败导致按钮完全无效。
toast 改为在未打开抽屉时也能挂载，并补源码与真实点击回归。

Co-authored-by: Cursor <cursoragent@cursor.com>
Co-authored-by: multica-agent <github@multica.ai>

tests/e2e/mobile-app.spec.js

@@ -355,6 +355,18 @@ test("system management pages render real content instead of placeholders", asyn
   await expect(page.locator("#m-sys-member-limit")).toBeVisible();
 });
 
+test("empty profile save click shows a toast instead of a dead button", async ({ page }) => {
+  await mockMobileApi(page);
+  await openMobile(page);
+  await navigateToFeature(page, "system/profile");
+  await expect(page.locator("[data-system-save-birth]")).toBeVisible();
+  await page.locator("#m-sys-birth-date").fill("");
+  await page.locator("#m-sys-birth-time").fill("");
+  await page.locator("[data-system-save-birth]").click();
+  await expect(page.locator("#m-toast.is-visible")).toBeVisible();
+  await expect(page.locator("#m-toast")).toContainText("请填写完整出生日期和时间");
+});
+
 test("non-admin cannot open system admin pages as placeholders", async ({ page }) => {
   await mockMobileApi(page, { auth: authSession("user", true) });
   await openMobile(page);