feat: DeerFlow 2.0 core capabilities — Phase 1.0 + 1.1

Phase 1.0 — Butler Mode UI:
- Hide "自动化" and "技能市场" entries from sidebar navigation
- Remove AutomationPanel and SkillMarket view rendering from App.tsx
- Simplify MainViewType to only 'chat'
- Main interface is now: chat + conversation list + detail panel only

Phase 1.1 — Mode Differentiation:
- Add subagent_enabled field to ChatModeConfig (Rust), StreamChatRequest (Tauri),
  gateway-client, kernel-client, saas-relay-client, and streamStore
- TaskTool is now only registered when subagent_enabled=true (Ultra mode)
- System prompt includes sub-agent delegation instructions only in Ultra mode
- Frontend transmits subagent_enabled from ChatMode config through the full stack

This connects the 4-tier mode selector (Flash/Thinking/Pro/Ultra) to actual
backend behavioral differences — Ultra mode now truly enables sub-agent delegation.

desktop/src/components/Sidebar.tsx

@@ -1,7 +1,7 @@
 import { useState } from 'react';
 import { motion, AnimatePresence } from 'framer-motion';
 import {
-  SquarePen, MessageSquare, Bot, Search, X, Settings, Zap, Sparkles
+  SquarePen, MessageSquare, Bot, Search, X, Settings
 } from 'lucide-react';
 import { ConversationList } from './ConversationList';
 import { CloneManager } from './CloneManager';
@@ -15,7 +15,7 @@ const sidebarTabVariants = {
   exit: { opacity: 0, transition: { duration: 0.1 } },
 };
 
-export type MainViewType = 'chat' | 'automation' | 'skills';
+export type MainViewType = 'chat';
 
 interface SidebarProps {
   onOpenSettings?: () => void;
@@ -89,23 +89,6 @@ export function Sidebar({
           智能体
         </button>
 
-        {/* Divider between primary nav and secondary tools */}
-        <div className="mx-1 my-1 border-t border-[#e8e6e1]/40 dark:border-gray-800" />
-
-        <button
-          onClick={() => onMainViewChange?.('automation')}
-          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"
-        >
-          <Zap className="w-4 h-4" />
-          自动化
-        </button>
-        <button
-          onClick={() => onMainViewChange?.('skills')}
-          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"
-        >
-          <Sparkles className="w-4 h-4" />
-          技能市场
-        </button>
       </div>
 
       {/* Divider */}