HEL-342: 管理总览 KPI 绑定真实 dashboard 接口

去掉写死的演示金额与账期进度，改由 /api/admin/dashboard 的 totals 与 period_progress 填充；无数据走空态。

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

tests/test_reminders_page.py

@@ -37,8 +37,8 @@ class RemindersPageSourceContractTests(unittest.TestCase):
         self.assertIn('id="reminder-tbody"', html)
         self.assertIn('id="reminder-tabs"', html)
         self.assertIn('id="reminder-detail-drawer"', html)
-        self.assertIn("design-system.css?v=11", html)
-        self.assertIn("app.js?v=16", html)
+        self.assertIn("design-system.css?v=12", html)
+        self.assertIn("app.js?v=17", html)
         pending = html.index('id="pending-reminders-card"')
         history = html.index('id="reminder-history-card"')
         send = html.index('id="send-reminder-card"')
@@ -135,7 +135,7 @@ class RemindersPageLayoutSmokeTests(unittest.TestCase):
 
     def test_send_flow_columns_and_no_page_overflow(self) -> None:
         html = (WEB / "admin.html").read_text(encoding="utf-8")
-        self.assertIn("app.js?v=16", html)
+        self.assertIn("app.js?v=17", html)
         with sync_playwright() as p:
             browser = p.chromium.launch()
             page = browser.new_page()