fix(web): Sidebar section label 修正 — main 不顯示標題，legacy 用分隔線

apps/web/src/components/layout/sidebar.tsx

@@ -159,17 +159,19 @@ export function Sidebar({
         {/* 4 分區菜單 */}
         {NAV_SECTIONS.map(section => (
           <div key={section.sectionKey} style={{ marginBottom: 4 }}>
-            {/* 分區標題（collapsed 時隱藏）*/}
-            {!collapsed && (
+            {/* 分區標題 — main 不顯示，legacy 顯示分隔線+標題 */}
+            {!collapsed && section.sectionLabel && (
               <div style={{
-                fontSize: 11,
+                fontSize: 10,
                 color: '#b0ad9f',
                 letterSpacing: '1.5px',
                 textTransform: 'uppercase' as const,
-                padding: '8px 12px 3px',
+                padding: '12px 12px 3px',
                 fontFamily: 'var(--font-body), monospace',
+                borderTop: '0.5px solid #e0ddd4',
+                marginTop: 4,
               }}>
-                {tSection(section.sectionKey)}
+                {section.sectionLabel}
               </div>
             )}
             {section.items.map(item => {