feat(HEL-251): 按确认稿实现登录页动态小K线人物

在桌面登录门户品牌空白带加入红绿小K线角色，支持焦点、密码遮挡、登录反馈和减少动态效果，且不移动原有文案与行情图。

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

tests/test_login_portal.py

@@ -44,6 +44,29 @@ class LoginPortalContractTests(unittest.TestCase):
         self.assertIn("padding-bottom: 0;", AUTH)
         self.assertNotIn("padding: 0 0 var(--statusbar-height);", AUTH)
 
+    def test_confirmed_mascots_fill_the_brand_gap(self) -> None:
+        for needle in (
+            'id="loginMascots"',
+            'aria-hidden="true"',
+            'class="login-mascot is-red"',
+            'class="login-mascot is-green"',
+            'class="login-mascot-back"',
+            'class="login-mascot-slit"',
+        ):
+            self.assertIn(needle, LOGIN)
+        for needle in (
+            "--login-mascot-red: #e8605a;",
+            "--login-mascot-green: #46be93;",
+            "--login-mascot-height: clamp(150px, 15vw, 260px);",
+        ):
+            self.assertIn(needle, TOKENS)
+        self.assertIn("flex: 1 1 auto;", AUTH)
+        self.assertIn(".login-mascots {", AUTH)
+        self.assertIn("prefers-reduced-motion: reduce", AUTH)
+        self.assertIn('next === "password"', LOGIN_JS)
+        self.assertIn("toggle-password", LOGIN_JS)
+        self.assertIn("celebrateLogin", LOGIN_JS)
+
     def test_portal_keeps_account_switch_and_theme_hooks(self) -> None:
         self.assertIn("data-switch-id", LOGIN_JS)
         self.assertIn("data-resume-id", LOGIN_JS)