✨ feat: Add custom request body editor with persistent message storage

- Add CustomRequestEditor component with JSON validation and real-time formatting
- Implement bidirectional sync between chat messages and custom request body
- Add persistent local storage for chat messages (separate from config)
- Remove redundant System Prompt field in custom mode
- Refactor configuration storage to separate messages and settings

New Features:
• Custom request body mode with JSON editor and syntax highlighting
• Real-time bidirectional synchronization between chat UI and custom request body
• Persistent message storage that survives page refresh
• Enhanced configuration export/import including message data
• Improved parameter organization with collapsible sections

Technical Changes:
• Add loadMessages/saveMessages functions in configStorage
• Update usePlaygroundState hook to handle message persistence
• Refactor SettingsPanel to remove System Prompt in custom mode
• Add STORAGE_KEYS constants for better storage key management
• Implement debounced auto-save for both config and messages
• Add hash-based change detection to prevent unnecessary updates

UI/UX Improvements:
• Disabled state styling for parameters in custom mode
• Warning banners and visual feedback for mode switching
• Mobile-responsive design for custom request editor
• Consistent styling with existing design system

web/src/utils/constants.js

@@ -1,21 +1,4 @@
-// Playground 相关常量
-export const DEFAULT_MESSAGES = [
-  {
-    role: 'user',
-    id: '2',
-    createAt: 1715676751919,
-    content: '你好',
-  },
-  {
-    role: 'assistant',
-    id: '3',
-    createAt: 1715676751919,
-    content: '你好，请问有什么可以帮助您的吗？',
-    reasoningContent: '',
-    isReasoningExpanded: false,
-  },
-];
-
+// ========== 消息相关常量 ==========
 export const MESSAGE_STATUS = {
   LOADING: 'loading',
   INCOMPLETE: 'incomplete',
@@ -29,21 +12,42 @@ export const MESSAGE_ROLES = {
   SYSTEM: 'system',
 };
 
+// 默认消息示例
+export const DEFAULT_MESSAGES = [
+  {
+    role: MESSAGE_ROLES.USER,
+    id: '2',
+    createAt: 1715676751919,
+    content: '你好',
+  },
+  {
+    role: MESSAGE_ROLES.ASSISTANT,
+    id: '3',
+    createAt: 1715676751919,
+    content: '你好，请问有什么可以帮助您的吗？',
+    reasoningContent: '',
+    isReasoningExpanded: false,
+  },
+];
+
+// ========== UI 相关常量 ==========
 export const DEBUG_TABS = {
   PREVIEW: 'preview',
   REQUEST: 'request',
   RESPONSE: 'response',
 };
 
+// ========== API 相关常量 ==========
 export const API_ENDPOINTS = {
   CHAT_COMPLETIONS: '/pg/chat/completions',
   USER_MODELS: '/api/user/models',
   USER_GROUPS: '/api/user/self/groups',
 };
 
+// ========== 配置默认值 ==========
 export const DEFAULT_CONFIG = {
   inputs: {
-    model: 'gpt-4',
+    model: 'gpt-4o',
     group: '',
     temperature: 0.7,
     top_p: 1,
@@ -65,14 +69,27 @@ export const DEFAULT_CONFIG = {
   },
   systemPrompt: '',
   showDebugPanel: false,
+  customRequestMode: false,
+  customRequestBody: '',
 };
 
+// ========== 正则表达式 ==========
 export const THINK_TAG_REGEX = /<think>([\s\S]*?)<\/think>/g;
 
+// ========== 错误消息 ==========
 export const ERROR_MESSAGES = {
   NO_TEXT_CONTENT: '此消息没有可复制的文本内容',
   INVALID_MESSAGE_TYPE: '无法复制此类型的消息内容',
   COPY_FAILED: '复制失败，请手动选择文本复制',
   COPY_HTTPS_REQUIRED: '复制功能需要 HTTPS 环境，请手动复制',
   BROWSER_NOT_SUPPORTED: '浏览器不支持复制功能，请手动复制',
+  JSON_PARSE_ERROR: '自定义请求体格式错误，请检查JSON格式',
+  API_REQUEST_ERROR: '请求发生错误',
+  NETWORK_ERROR: '网络连接失败或服务器无响应',
+};
+
+// ========== 存储键名 ==========
+export const STORAGE_KEYS = {
+  CONFIG: 'playground_config',
+  MESSAGES: 'playground_messages',
 };