feat(desktop): DeerFlow visual redesign + stream hang fix + intelligence client

DeerFlow frontend visual overhaul:
- Card-style input box (white rounded card, textarea top, actions bottom)
- Dropdown mode selector (闪速/思考/Pro/Ultra with icons+descriptions)
- Colored quick-action chips (小惊喜/写作/研究/收集/学习)
- Minimal top bar (title + token count + export)
- Warm gray color system (#faf9f6 bg, #f5f4f1 sidebar, #e8e6e1 border)
- DeerFlow-style sidebar (新对话/对话/智能体 nav)
- Reasoning block, tool call chain, task progress visualization
- Streaming text, model selector, suggestion chips components
- Resizable artifact panel with drag handle
- Virtualized message list for 100+ messages

Bug fixes:
- Stream hang: GatewayClient onclose code 1000 now calls onComplete
- WebView2 textarea border: CSS !important override for UA styles
- Gateway stream event handling (response/phase/tool_call types)

Intelligence client:
- Unified client with fallback drivers (compactor/heartbeat/identity/memory/reflection)
- Gateway API types and type conversions

desktop/src/components/FirstConversationPrompt.tsx

@@ -1,19 +1,45 @@
 /**
- * FirstConversationPrompt - Welcome prompt for new Agents
+ * FirstConversationPrompt - Welcome prompt for new conversations
  *
- * Displays a personalized welcome message and quick start suggestions
- * when entering a new Agent's chat for the first time.
+ * DeerFlow-inspired design:
+ * - Centered layout with emoji greeting
+ * - Input bar embedded in welcome screen
+ * - Horizontal quick-action chips (colored pills)
+ * - Clean, minimal aesthetic
  */
 import { motion } from 'framer-motion';
-import { Lightbulb, ArrowRight } from 'lucide-react';
+import {
+  Sparkles,
+  PenLine,
+  Microscope,
+  Layers,
+  GraduationCap,
+} from 'lucide-react';
 import { cn } from '../lib/utils';
 import {
   generateWelcomeMessage,
-  getQuickStartSuggestions,
   getScenarioById,
-  type QuickStartSuggestion,
 } from '../lib/personality-presets';
 import type { Clone } from '../store/agentStore';
+import { useChatStore } from '../store/chatStore';
+
+// Quick action chip definitions — DeerFlow-style colored pills
+const QUICK_ACTIONS = [
+  { key: 'surprise', label: '小惊喜', icon: Sparkles, color: 'text-orange-500' },
+  { key: 'write', label: '写作', icon: PenLine, color: 'text-blue-500' },
+  { key: 'research', label: '研究', icon: Microscope, color: 'text-purple-500' },
+  { key: 'collect', label: '收集', icon: Layers, color: 'text-green-500' },
+  { key: 'learn', label: '学习', icon: GraduationCap, color: 'text-indigo-500' },
+];
+
+// Pre-filled prompts for each quick action
+const QUICK_ACTION_PROMPTS: Record<string, string> = {
+  surprise: '给我一个小惊喜吧！来点创意的',
+  write: '帮我写一篇文章，主题你来定',
+  research: '帮我做一个深度研究分析',
+  collect: '帮我收集整理一些有用的信息',
+  learn: '我想学点新东西，教我一些有趣的知识',
+};
 
 interface FirstConversationPromptProps {
   clone: Clone;
@@ -25,7 +51,15 @@ export function FirstConversationPrompt({
   clone,
   onSelectSuggestion,
 }: FirstConversationPromptProps) {
-  // Generate welcome message
+  const chatMode = useChatStore((s) => s.chatMode);
+
+  const modeGreeting: Record<string, string> = {
+    flash: '快速回答，即时响应',
+    thinking: '深度分析，逐步推理',
+    pro: '专业规划，系统思考',
+    ultra: '多代理协作，全能力调度',
+  };
+
   const welcomeMessage = generateWelcomeMessage({
     userName: clone.userName,
     agentName: clone.nickname || clone.name,
@@ -34,11 +68,9 @@ export function FirstConversationPrompt({
     scenarios: clone.scenarios,
   });
 
-  // Get quick start suggestions based on scenarios
-  const suggestions = getQuickStartSuggestions(clone.scenarios || []);
-
-  const handleSuggestionClick = (suggestion: QuickStartSuggestion) => {
-    onSelectSuggestion?.(suggestion.text);
+  const handleQuickAction = (key: string) => {
+    const prompt = QUICK_ACTION_PROMPTS[key] || '你好！';
+    onSelectSuggestion?.(prompt);
   };
 
   return (
@@ -48,48 +80,63 @@ export function FirstConversationPrompt({
       exit={{ opacity: 0, y: -10 }}
       className="flex flex-col items-center justify-center py-12 px-4"
     >
-      {/* Avatar with emoji */}
-      <div className="mb-6">
-        <div className="w-20 h-20 rounded-2xl bg-gradient-to-br from-primary/20 to-primary/10 dark:from-primary/30 dark:to-primary/20 flex items-center justify-center shadow-lg">
-          <span className="text-4xl">{clone.emoji || '🦞'}</span>
-        </div>
-      </div>
+      {/* Greeting emoji */}
+      <div className="text-5xl mb-4">{clone.emoji || '👋'}</div>
+
+      {/* Title */}
+      <motion.h1
+        initial={{ opacity: 0, y: 10 }}
+        animate={{ opacity: 1, y: 0 }}
+        transition={{ delay: 0.1, duration: 0.5 }}
+        className="text-2xl font-semibold text-gray-900 dark:text-gray-100 mb-2"
+      >
+        你好，欢迎回来！
+      </motion.h1>
+
+      {/* Mode-aware subtitle */}
+      <motion.p
+        initial={{ opacity: 0 }}
+        animate={{ opacity: 1 }}
+        transition={{ delay: 0.2, duration: 0.4 }}
+        className="text-sm text-orange-500 dark:text-orange-400 font-medium mb-4 flex items-center gap-1.5"
+      >
+        <Sparkles className="w-3.5 h-3.5" />
+        {modeGreeting[chatMode] || '智能对话，随时待命'}
+      </motion.p>
 
       {/* Welcome message */}
       <div className="text-center max-w-md mb-8">
-        <p className="text-lg text-gray-700 dark:text-gray-200 whitespace-pre-line leading-relaxed">
+        <p className="text-sm text-gray-500 dark:text-gray-400 leading-relaxed">
           {welcomeMessage}
         </p>
       </div>
 
-      {/* Quick start suggestions */}
-      <div className="w-full max-w-lg space-y-2">
-        <div className="flex items-center gap-2 text-sm text-gray-500 dark:text-gray-400 mb-3">
-          <Lightbulb className="w-4 h-4" />
-          <span>快速开始</span>
-        </div>
-
-        {suggestions.map((suggestion, index) => (
-          <motion.button
-            key={index}
-            initial={{ opacity: 0, x: -20 }}
-            animate={{ opacity: 1, x: 0 }}
-            transition={{ delay: index * 0.1 }}
-            onClick={() => handleSuggestionClick(suggestion)}
-            className={cn(
-              'w-full flex items-center gap-3 px-4 py-3 rounded-xl',
-              'bg-gray-50 dark:bg-gray-800/50 border border-gray-200 dark:border-gray-700',
-              'hover:bg-gray-100 dark:hover:bg-gray-800 hover:border-primary/30',
-              'transition-all duration-200 group text-left'
-            )}
-          >
-            <span className="text-xl flex-shrink-0">{suggestion.icon}</span>
-            <span className="flex-1 text-sm text-gray-700 dark:text-gray-200">
-              {suggestion.text}
-            </span>
-            <ArrowRight className="w-4 h-4 text-gray-400 group-hover:text-primary transition-colors flex-shrink-0" />
-          </motion.button>
-        ))}
+      {/* Quick action chips — DeerFlow-style horizontal colored pills */}
+      <div className="flex items-center justify-center gap-2 flex-wrap">
+        {QUICK_ACTIONS.map((action, index) => {
+          const ActionIcon = action.icon;
+          return (
+            <motion.button
+              key={action.key}
+              initial={{ opacity: 0, y: 8 }}
+              animate={{ opacity: 1, y: 0 }}
+              transition={{ delay: 0.3 + index * 0.05, duration: 0.2 }}
+              onClick={() => handleQuickAction(action.key)}
+              className={cn(
+                'flex items-center gap-2 px-4 py-2',
+                'bg-white dark:bg-gray-800',
+                'border border-gray-200 dark:border-gray-700',
+                'rounded-full text-sm text-gray-600 dark:text-gray-300',
+                'hover:border-gray-300 dark:hover:border-gray-600',
+                'hover:bg-gray-50 dark:hover:bg-gray-750',
+                'transition-all duration-150'
+              )}
+            >
+              <ActionIcon className={`w-4 h-4 ${action.color}`} />
+              <span>{action.label}</span>
+            </motion.button>
+          );
+        })}
       </div>
 
       {/* Scenario tags */}