feat: TypeScript + Electron v2 重构 - 纯桌面版

- 全面迁移到 TypeScript，严格类型定义
- 放弃 Web 版，专注 Electron 桌面应用
- 主进程模块化：main.ts, preload.ts, menu.ts, tray.ts, ipc.ts, utils.ts
- 渲染进程完整迁移所有功能组件
- 删除 PWA 相关文件 (sw.js, manifest.json)
- 删除 Web 版降级逻辑
- 保留所有核心功能：流式对话、多模型、Think推理、多模态、RAG知识库、Agent预设、历史管理
- 保留 Windows 11 Fluent Design 暗色主题样式

src/main/preload.ts

@@ -0,0 +1,34 @@
+/**
+ * Metona Ollama Desktop - Preload 脚本
+ */
+
+import { contextBridge, ipcRenderer } from 'electron';
+
+contextBridge.exposeInMainWorld('metonaDesktop', {
+  isDesktop: true,
+  info: () => ipcRenderer.invoke('app:info'),
+  dialog: {
+    openFile: (filters?: unknown) => ipcRenderer.invoke('dialog:openFile', { filters }),
+    saveFile: (options?: unknown) => ipcRenderer.invoke('dialog:saveFile', options)
+  },
+  fs: {
+    readFile: (filePath: string) => ipcRenderer.invoke('fs:readFile', filePath),
+    writeFile: (filePath: string, content: string) => ipcRenderer.invoke('fs:writeFile', filePath, content)
+  },
+  notify: (title: string, body: string) => ipcRenderer.invoke('notify', title, body),
+  window: {
+    minimize: () => ipcRenderer.invoke('window:minimize'),
+    maximize: () => ipcRenderer.invoke('window:maximize'),
+    close: () => ipcRenderer.invoke('window:close')
+  },
+  openExternal: (url: string) => ipcRenderer.invoke('shell:openExternal', url),
+  onMenuAction: (callback: (action: string) => void) => {
+    ipcRenderer.on('menu-action', (_: unknown, action: string) => callback(action));
+  },
+  onTrayAction: (callback: (action: string) => void) => {
+    ipcRenderer.on('tray-action', (_: unknown, action: string) => callback(action));
+  },
+  removeAllListeners: (channel: string) => {
+    ipcRenderer.removeAllListeners(channel);
+  }
+});