feat: 添加工作空间面板 - 右侧终端/文件浏览器

- 新增主进程 workspace.ts：spawn 进程管理，流式输出，安全检查
- IPC 双向通信：workspace:exec（on/send 模式，无超时限制）
- preload 暴露 workspace API
- 渲染进程 workspace-panel.ts：多终端 Tab、ANSI 颜色渲染、文件浏览器
- 设置面板添加工作空间目录配置
- 启动时自动创建 workspace 目录
- 窗口关闭时自动清理所有子进程
- 帮助文档更新

src/renderer/types.d.ts

@@ -189,6 +189,19 @@ export interface DocInfo {
 
 // ── 桌面 Bridge 类型 ──
 
+export interface WorkspaceFileEntry {
+  name: string;
+  type: 'file' | 'directory';
+  size: number | null;
+  modified: string;
+}
+
+export interface WorkspaceDirResult {
+  success: boolean;
+  entries?: WorkspaceFileEntry[];
+  error?: string;
+}
+
 export interface MetonaDesktopAPI {
   isDesktop: boolean;
   info: () => Promise<AppInfo>;
@@ -216,6 +229,16 @@ export interface MetonaDesktopAPI {
   onTrayAction: (callback: (action: string) => void) => void;
   onAppQuit: (callback: () => void) => void;
   removeAllListeners: (channel: string) => void;
+  workspace: {
+    getDir: () => Promise<{ dir: string; defaultDir: string }>;
+    setDir: (dir: string) => Promise<{ success: boolean; dir?: string; error?: string }>;
+    listDir: (dirPath?: string) => Promise<WorkspaceDirResult>;
+    readFile: (filePath: string) => Promise<{ success: boolean; content?: string; path?: string; error?: string; truncated?: boolean; lines?: number }>;
+    exec: (params: { id: string; command: string; cwd?: string }) => void;
+    kill: (id: string) => void;
+    onOutput: (callback: (data: { id: string; type: 'stdout' | 'stderr'; data: string }) => void) => void;
+    onExit: (callback: (data: { id: string; code: number | null }) => void) => void;
+  };
 }
 
 export interface AppInfo {