style: 登录页高度与滚动行为修正

登录页主区域改为 height 100% 避免内部双滚动条，移动端恢复 min-height 并允许整体滚动。

frontend/src/views/login/LoginView.vue

@@ -122,18 +122,17 @@ async function handleLogin() {
 
 <style scoped lang="scss">
 .login-page {
-  min-height: 100vh;
-  min-height: 100dvh;
+  height: 100vh;
+  height: 100dvh;
   display: grid;
   grid-template-columns: minmax(0, 58fr) minmax(500px, 42fr);
-  overflow-x: hidden;
-  overflow-y: auto;
+  overflow: hidden;
   background: #fcfcfe;
 }
 
 .login-visual {
-  min-height: 100vh;
-  min-height: 100dvh;
+  min-height: 0;
+  height: 100%;
   position: relative;
   color: #fff;
   background-color: #121127;
@@ -152,7 +151,8 @@ async function handleLogin() {
 }
 
 .login-visual-content {
-  min-height: inherit;
+  min-height: 0;
+  height: 100%;
   position: relative;
   z-index: 1;
   display: flex;
@@ -204,8 +204,8 @@ async function handleLogin() {
 }
 
 .login-panel {
-  min-height: 100vh;
-  min-height: 100dvh;
+  min-height: 0;
+  height: 100%;
   position: relative;
   display: grid;
   place-items: center;
@@ -514,6 +514,9 @@ async function handleLogin() {
 @media (max-width: 900px) {
   .login-page {
     display: block;
+    height: auto;
+    min-height: 100vh;
+    min-height: 100dvh;
     overflow: auto;
   }
 
@@ -522,6 +525,7 @@ async function handleLogin() {
   }
 
   .login-panel {
+    height: auto;
     min-height: 100vh;
     min-height: 100dvh;
     padding: 116px 32px 84px;