新增: Tauri 2.0 桌面版脚手架(B0)

- src-tauri/ 完整项目结构: Cargo.toml / build.rs / tauri.conf.json
- Rust 入口 lib.rs: ping IPC 命令验证双向通信
- 应用图标生成(SVG → ico/icns/png 多尺寸)
- Tauri 窗口配置: 1280×800, 最小 900×600, 可缩放
- package.json 新增 tauri / tauri:dev / tauri:build 脚本
- vite.config.ts 环境检测: Tauri 模式端口 5173, Web 模式 8080
- @tauri-apps/cli + @tauri-apps/api 依赖安装
- cargo check 编译通过,前端构建不受影响
- 桌面版与 Web 版共享同一套前端代码

src-tauri/tauri.conf.json

@@ -0,0 +1,39 @@
+{
+  "$schema": "https://schema.tauri.app/config/2",
+  "productName": "u-ppt",
+  "version": "1.0.0",
+  "identifier": "com.uppt.desktop",
+  "build": {
+    "frontendDist": "../dist",
+    "devUrl": "http://localhost:5173",
+    "beforeDevCommand": "npm run dev",
+    "beforeBuildCommand": "npm run build"
+  },
+  "app": {
+    "windows": [
+      {
+        "title": "u-ppt · 在线演示工具",
+        "width": 1280,
+        "height": 800,
+        "minWidth": 900,
+        "minHeight": 600,
+        "resizable": true,
+        "fullscreen": false
+      }
+    ],
+    "security": {
+      "csp": null
+    }
+  },
+  "bundle": {
+    "active": true,
+    "targets": "all",
+    "icon": [
+      "icons/32x32.png",
+      "icons/128x128.png",
+      "icons/128x128@2x.png",
+      "icons/icon.icns",
+      "icons/icon.ico"
+    ]
+  }
+}