fix(desktop): 功能验证 6 项缺陷修复

- ISS-002: SkillInfoResponse 增加 source/path 字段，修复技能系统显示 0 个
- ISS-003: Sidebar 添加自动化/技能市场导航入口 + App 返回按钮
- ISS-004: SaaS fetchAvailableModels 添加 .catch() 防限流崩溃
- ISS-006: SaaSSettings/PricingPage 包裹 ErrorBoundary 防白屏
- ISS-008: listModels 加载 localStorage 自定义模型，修复仅显示 1 个模型
- configStore listSkills 映射添加 source/path 转发

desktop/src/App.tsx

@@ -486,6 +486,16 @@ function App() {
                 animate="animate"
                 className="h-full overflow-y-auto"
               >
+                <div className="sticky top-0 z-10 flex items-center gap-2 px-4 py-2 bg-white/80 dark:bg-gray-900/80 backdrop-blur-sm border-b border-gray-200 dark:border-gray-800">
+                  <button
+                    onClick={() => handleMainViewChange('chat')}
+                    className="p-1.5 hover:bg-black/5 dark:hover:bg-white/5 rounded-md transition-colors text-gray-600 dark:text-gray-400"
+                    title="返回聊天"
+                  >
+                    <svg xmlns="http://www.w3.org/2000/svg" className="w-4 h-4" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round"><path d="m15 18-6-6 6-6"/></svg>
+                  </button>
+                  <span className="text-sm font-medium text-gray-900 dark:text-gray-100">自动化</span>
+                </div>
                 <AutomationPanel />
               </motion.div>
             ) : mainContentView === 'skills' ? (
@@ -495,7 +505,19 @@ function App() {
                 animate="animate"
                 className="h-full overflow-hidden"
               >
-                <SkillMarket />
+                <div className="flex items-center gap-2 px-4 py-2 border-b border-gray-200 dark:border-gray-800">
+                  <button
+                    onClick={() => handleMainViewChange('chat')}
+                    className="p-1.5 hover:bg-black/5 dark:hover:bg-white/5 rounded-md transition-colors text-gray-600 dark:text-gray-400"
+                    title="返回聊天"
+                  >
+                    <svg xmlns="http://www.w3.org/2000/svg" className="w-4 h-4" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round"><path d="m15 18-6-6 6-6"/></svg>
+                  </button>
+                  <span className="text-sm font-medium text-gray-900 dark:text-gray-100">技能市场</span>
+                </div>
+                <div className="h-[calc(100%-40px)] overflow-auto">
+                  <SkillMarket />
+                </div>
               </motion.div>
             ) : (
               <ChatArea />