✨ 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/hooks/useDataLoader.js

@@ -0,0 +1,70 @@
+import { useCallback, useEffect } from 'react';
+import { useTranslation } from 'react-i18next';
+import { API, showError } from '../helpers/index.js';
+import { API_ENDPOINTS } from '../utils/constants';
+import { processModelsData, processGroupsData } from '../utils/apiUtils';
+
+export const useDataLoader = (
+  userState,
+  inputs,
+  handleInputChange,
+  setModels,
+  setGroups
+) => {
+  const { t } = useTranslation();
+
+  const loadModels = useCallback(async () => {
+    try {
+      const res = await API.get(API_ENDPOINTS.USER_MODELS);
+      const { success, message, data } = res.data;
+
+      if (success) {
+        const { modelOptions, selectedModel } = processModelsData(data, inputs.model);
+        setModels(modelOptions);
+
+        if (selectedModel !== inputs.model) {
+          handleInputChange('model', selectedModel);
+        }
+      } else {
+        showError(t(message));
+      }
+    } catch (error) {
+      showError(t('加载模型失败'));
+    }
+  }, [inputs.model, handleInputChange, setModels, t]);
+
+  const loadGroups = useCallback(async () => {
+    try {
+      const res = await API.get(API_ENDPOINTS.USER_GROUPS);
+      const { success, message, data } = res.data;
+
+      if (success) {
+        const userGroup = userState?.user?.group || JSON.parse(localStorage.getItem('user'))?.group;
+        const groupOptions = processGroupsData(data, userGroup);
+        setGroups(groupOptions);
+
+        const hasCurrentGroup = groupOptions.some(option => option.value === inputs.group);
+        if (!hasCurrentGroup) {
+          handleInputChange('group', groupOptions[0]?.value || '');
+        }
+      } else {
+        showError(t(message));
+      }
+    } catch (error) {
+      showError(t('加载分组失败'));
+    }
+  }, [userState, inputs.group, handleInputChange, setGroups, t]);
+
+  // 自动加载数据
+  useEffect(() => {
+    if (userState?.user) {
+      loadModels();
+      loadGroups();
+    }
+  }, [userState?.user, loadModels, loadGroups]);
+
+  return {
+    loadModels,
+    loadGroups
+  };
+};