style(portal+login): 7 个 logo 占位符 '医' 换为 logo.png 图片

- components/PortalShell.vue (navbar + footer, 共享给 3 个注册页)
- views/portal/Home.vue (navbar + footer)
- views/portal/ArticleView.vue (navbar + footer)
- views/portal/SpecialPlanDetail.vue (navbar + footer)
- views/portal/Publicity.vue (navbar + footer)
- views/portal/PublicityDetail.vue (navbar + footer)
- views/auth/Login.vue (登录页 logo)

每个 .logo-icon / .footer-logo-icon:
  HTML: <div class='logo-icon'>医</div> → 含 <img src='/logo.png'>
  CSS:  删 background/color/font-size/font-weight (字标样式)
       改 overflow:hidden + object-fit:contain (图片容器)

全站 '医' 字符占位符清零.

ry-vue3/src/views/auth/Login.vue

@@ -3,7 +3,7 @@
     <!-- 顶部导航 -->
     <header class="header">
       <a class="logo" @click.prevent="$router.push('/portal/home')">
-        <div class="logo-icon">医</div>
+        <div class="logo-icon"><img src="/logo.png" alt="logo" /></div>
         <div class="logo-text">
           <span class="logo-title">北京整合医学学会</span>
           <span class="logo-subtitle">Beijing Association of Holistic Integrative Medicine</span>
@@ -518,14 +518,13 @@ onUnmounted(() => {
 .login-page .logo-icon{
     width: 36px;
     height: 36px;
-    background: var(--brand-primary);
-    color: #fff;
+    background: #fff;
     display: flex;
     align-items: center;
     justify-content: center;
-    font-size: 18px;
-    font-weight: 600;
+    overflow: hidden;
 }
+.login-page .logo-icon img { width: 100%; height: 100%; object-fit: contain; display: block; }
 
 .login-page .logo-text{
     display: flex;