style: tighten settings and account menu

src/components/Sidebar.scss

@@ -53,7 +53,7 @@
   z-index: 12;
   border: 1px solid var(--border-color);
   border-radius: 12px;
-  background: var(--bg-secondary);
+  background: var(--bg-secondary-solid, var(--bg-primary));
   display: flex;
   flex-direction: column;
   gap: 4px;

src/pages/SettingsPage.scss

@@ -32,7 +32,7 @@
   align-items: flex-start;
   justify-content: space-between;
   gap: 20px;
-  margin-bottom: 18px;
+  margin-bottom: 14px;
   flex-shrink: 0;
 
   h1 {
@@ -46,14 +46,6 @@
 .settings-title-block {
   display: flex;
   flex-direction: column;
-  gap: 6px;
-
-  p {
-    margin: 0;
-    font-size: 13px;
-    color: var(--text-tertiary);
-    line-height: 1.6;
-  }
 }
 
 .settings-actions {

src/pages/SettingsPage.tsx

@@ -2098,7 +2098,6 @@ function SettingsPage({ onClose }: SettingsPageProps = {}) {
         <div className="settings-header">
           <div className="settings-title-block">
             <h1>设置</h1>
-            <p>在这里集中调整 WeFlow 的功能、外观与数据行为。</p>
           </div>
           <div className="settings-actions">
             <button className="btn btn-secondary" onClick={handleTestConnection} disabled={isLoading || isTesting}>