feat(zip): 루트 파일(extras) 포함 및 site.webmanifest JSON 검증 추가\n\n- favicon.ico/site.webmanifest/robots.txt ZIP 포함 지원\n- 잘못된 manifest JSON 시 에러\n- 테스트(phase4) 추가 및 통과

lib/exporter/zip.ts

@@ -5,6 +5,8 @@ export type BuildZipInput = {
   css: string
   js: string
   assets?: Record<string, Uint8Array>
+  // root-level extra files like favicon.ico, site.webmanifest, robots.txt
+  extras?: Record<string, Uint8Array>
 }
 
 export async function buildZip(input: BuildZipInput): Promise<Uint8Array> {
@@ -19,6 +21,22 @@ export async function buildZip(input: BuildZipInput): Promise<Uint8Array> {
       zip.file(path, buf as unknown as Buffer)
     }
   }
+  if (input.extras) {
+    // validate manifest if present
+    if (Object.prototype.hasOwnProperty.call(input.extras, 'site.webmanifest')) {
+      try {
+        const manifestBytes = input.extras['site.webmanifest']
+        const manifestStr = Buffer.from(manifestBytes).toString('utf8')
+        JSON.parse(manifestStr)
+      } catch {
+        throw new Error('Invalid site.webmanifest JSON')
+      }
+    }
+    for (const [path, bytes] of Object.entries(input.extras)) {
+      const buf = Buffer.from(bytes)
+      zip.file(path, buf as unknown as Buffer)
+    }
+  }
   const content = await zip.generateAsync({ type: 'uint8array' })
   return content
 }