陶泥儿产物读取按已知体积预分配

- read_package_bytes 接收调用方已验证的 expected_bytes，用 Vec::with_capacity
- 接近 200 MiB 的包不再因反复扩容多复制约一倍数据

apps/ai-game-creator-shell/src-tauri/src/export/draft/taonier/build.rs

@@ -239,7 +239,7 @@ pub(crate) fn read_artifact_package(root: &Path) -> Result<TaonierArtifactPackag
     }
     ensure_within_platform_package_limit(metadata.len())?;
 
-    let (package_bytes, package_sha256) = read_package_bytes(&path)?;
+    let (package_bytes, package_sha256) = read_package_bytes(&path, metadata.len())?;
     if package_bytes.len() as u64 != metadata.len() {
         // 读取期间文件被替换：宁可让作者重新导出，也不上传一份哈希与内容对不上的包。
         return Err("陶泥儿产物在读取期间发生变化，请重新导出".to_string());
@@ -255,11 +255,14 @@ pub(crate) fn read_artifact_package(root: &Path) -> Result<TaonierArtifactPackag
 }
 
 /// 一遍读完产物并同时算 sha256：不为了哈希再读一次盘。上限之外立即失败，避免把超大文件读进内存。
-fn read_package_bytes(path: &Path) -> Result<(Vec<u8>, String), String> {
+///
+/// 调用方已经确认过 `expected_bytes` 在上限内，按它预分配容量即可，避免接近 200 MiB 的包在
+/// 反复扩容时多复制约一倍数据。
+fn read_package_bytes(path: &Path, expected_bytes: u64) -> Result<(Vec<u8>, String), String> {
     let mut file = std::fs::File::open(path)
         .map_err(|error| format!("打开陶泥儿产物失败：{}：{error}", path.display()))?;
     let mut hasher = Sha256::new();
-    let mut bytes = Vec::new();
+    let mut bytes = Vec::with_capacity(expected_bytes as usize);
     let mut buffer = vec![0u8; PACKAGE_READ_CHUNK_BYTES];
     loop {
         let read = file