feat: 添加 knip 冗余代码检查工具

配置 knip.json 检测未使用的文件、exports、依赖等。
新增 check:unused script，运行 knip-bun 扫描死代码。

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

knip.json

@@ -0,0 +1,22 @@
+{
+	"$schema": "https://unpkg.com/knip@6/schema.json",
+	"entry": ["src/entrypoints/cli.tsx"],
+	"project": ["src/**/*.{ts,tsx}"],
+	"ignore": ["src/types/**", "src/**/*.d.ts"],
+	"ignoreDependencies": [
+		"@ant/*",
+		"react-compiler-runtime",
+		"@anthropic-ai/mcpb",
+		"@anthropic-ai/sandbox-runtime"
+	],
+	"ignoreBinaries": ["bun"],
+	"workspaces": {
+		"packages/*": {
+			"entry": ["src/index.ts"],
+			"project": ["src/**/*.ts"]
+		},
+		"packages/@ant/*": {
+			"ignore": ["**"]
+		}
+	}
+}