feat(desktop): simple mode UI — ChatArea compact + SimpleSidebar + RightPanel dual-mode

Adapt ChatArea for compact/butler mode:
- Add onOpenDetail prop for expanding to full view
- Remove inline export dialog (moved to detail view)
- Replace SquarePen with ClipboardList icon

Add SimpleSidebar component for butler simple mode:
- Two tabs: 对话 / 行业资讯
- Quick suggestion buttons
- Minimal navigation

RightPanel refactoring for dual-mode support:
- Detect simple vs professional mode
- Conditional rendering based on butler mode state

desktop/src/components/SimpleSidebar.tsx

@@ -0,0 +1,120 @@
+/**
+ * SimpleSidebar - Trae Solo 风格的简洁侧边栏
+ *
+ * 仅显示：对话列表 + 行业资讯
+ * 底部：模式切换 + 设置
+ */
+
+import { useState } from 'react';
+import {
+  MessageSquare, Settings, LayoutGrid,
+  Search, X, Newspaper,
+} from 'lucide-react';
+import { ConversationList } from './ConversationList';
+
+interface SimpleSidebarProps {
+  onOpenSettings?: () => void;
+  onToggleMode?: () => void;
+}
+
+type Tab = 'conversations' | 'news';
+
+export function SimpleSidebar({ onOpenSettings, onToggleMode }: SimpleSidebarProps) {
+  const [activeTab, setActiveTab] = useState<Tab>('conversations');
+  const [searchQuery, setSearchQuery] = useState('');
+
+  return (
+    <aside className="w-64 sidebar-bg border-r border-[#e8e6e1] dark:border-gray-800 flex flex-col h-full shrink-0">
+      {/* Logo area */}
+      <div className="h-14 flex items-center px-4 border-b border-[#e8e6e1]/50 dark:border-gray-800">
+        <span className="text-lg font-semibold tracking-tight bg-gradient-to-r from-orange-500 to-amber-500 bg-clip-text text-transparent">
+          ZCLAW
+        </span>
+      </div>
+
+      {/* Tab 切换: 对话 / 行业资讯 */}
+      <div className="flex border-b border-[#e8e6e1]/50 dark:border-gray-800">
+        <button
+          onClick={() => setActiveTab('conversations')}
+          className={`flex-1 flex items-center justify-center gap-1.5 py-2.5 text-xs font-medium transition-colors ${
+            activeTab === 'conversations'
+              ? 'text-gray-900 dark:text-gray-100 border-b-2 border-orange-500'
+              : 'text-gray-500 dark:text-gray-400 hover:text-gray-700 dark:hover:text-gray-300'
+          }`}
+        >
+          <MessageSquare className="w-3.5 h-3.5" />
+          对话
+        </button>
+        <button
+          onClick={() => setActiveTab('news')}
+          className={`flex-1 flex items-center justify-center gap-1.5 py-2.5 text-xs font-medium transition-colors ${
+            activeTab === 'news'
+              ? 'text-gray-900 dark:text-gray-100 border-b-2 border-orange-500'
+              : 'text-gray-500 dark:text-gray-400 hover:text-gray-700 dark:hover:text-gray-300'
+          }`}
+        >
+          <Newspaper className="w-3.5 h-3.5" />
+          行业资讯
+        </button>
+      </div>
+
+      {/* 内容区域 */}
+      <div className="flex-1 overflow-hidden">
+        {activeTab === 'conversations' && (
+          <div className="p-2 h-full overflow-y-auto">
+            {/* 搜索框 */}
+            <div className="relative mb-2">
+              <Search className="absolute left-3 top-1/2 -translate-y-1/2 text-gray-400 w-4 h-4" />
+              <input
+                type="text"
+                placeholder="搜索对话..."
+                value={searchQuery}
+                onChange={(e) => setSearchQuery(e.target.value)}
+                className="w-full pl-9 pr-8 py-1.5 bg-white/60 dark:bg-gray-800 border border-[#e8e6e1] dark:border-gray-700 rounded-lg text-sm focus:outline-none focus:border-gray-400 transition-all text-gray-700 dark:text-gray-300 placeholder-gray-400"
+              />
+              {searchQuery && (
+                <button
+                  onClick={() => setSearchQuery('')}
+                  className="absolute right-2 top-1/2 -translate-y-1/2 p-1 hover:bg-gray-200 dark:hover:bg-gray-700 rounded text-gray-400"
+                >
+                  <X className="w-3 h-3" />
+                </button>
+              )}
+            </div>
+            <ConversationList searchQuery={searchQuery} />
+          </div>
+        )}
+
+        {activeTab === 'news' && (
+          <div className="p-3 h-full overflow-y-auto">
+            <div className="flex flex-col items-center justify-center py-12 text-gray-400 dark:text-gray-500">
+              <Newspaper className="w-10 h-10 mb-3 opacity-50" />
+              <p className="text-sm">行业资讯</p>
+              <p className="text-xs mt-1">开发中，敬请期待</p>
+            </div>
+          </div>
+        )}
+      </div>
+
+      {/* 底部操作栏 */}
+      <div className="p-2 border-t border-[#e8e6e1] dark:border-gray-700 space-y-1">
+        <button
+          onClick={onToggleMode}
+          className="w-full flex items-center gap-3 px-3 py-2 rounded-lg text-sm text-gray-600 dark:text-gray-400 hover:bg-black/5 dark:hover:bg-white/5 transition-colors"
+        >
+          <LayoutGrid className="w-4 h-4" />
+          <span>专业模式</span>
+        </button>
+        <button
+          onClick={onOpenSettings}
+          aria-label="打开设置"
+          title="设置和更多"
+          className="w-full flex items-center gap-3 px-3 py-2 rounded-lg text-sm text-gray-600 dark:text-gray-400 hover:bg-black/5 dark:hover:bg-white/5 transition-colors"
+        >
+          <Settings className="w-4 h-4" />
+          <span>设置</span>
+        </button>
+      </div>
+    </aside>
+  );
+}