feat: 前端迁移至 TypeScript，集成 Biome 格式化与代码检查

- app.js → app.ts：添加完整类型标注、接口定义
- audio-processor.js → audio-processor.ts：AudioWorklet 类型化
- vite.config.js → vite.config.ts
- 添加 tsconfig.json、vite-env.d.ts
- 集成 Biome 默认配置（lint + format），通过全部检查
- package.json 添加 check/typecheck 脚本
- index.html 修复无障碍问题（button type、SVG title）

web/package.json

@@ -1,12 +1,16 @@
 {
-  "name": "voicepaste-web",
-  "private": true,
-  "scripts": {
-    "dev": "vite",
-    "build": "vite build",
-    "preview": "vite preview"
-  },
-  "devDependencies": {
-    "vite": "^7.3.1"
-  }
+	"name": "voicepaste-web",
+	"private": true,
+	"scripts": {
+		"dev": "vite",
+		"build": "vite build",
+		"preview": "vite preview",
+		"check": "biome check .",
+		"typecheck": "tsc --noEmit"
+	},
+	"devDependencies": {
+		"@biomejs/biome": "^2.4.4",
+		"typescript": "^5.9.3",
+		"vite": "^7.3.1"
+	}
 }