[BUG] Incorrect Hash Verification in BUCK Upload API

[jjl9807]

While testing the BUCK upload API, I encountered the following error:

Buck API error: Hash mismatch: expected 3873e6d99a2a6e71f404f903e6867e49272ff987, got 5349b3b7fb470ed14e192cfab5a399f9f1ddc464

After investigation, I found that the API incorrectly implements hash verification logic by using the Git blob ID as the actual content hash:

https://github.com/web3infra-foundation/mega/blob/3efbf3b4f70c4dca1851820ae1f6cc5ff0bcae9d/jupiter/src/service/buck_service.rs#L760-L785

This is erroneous because Git computes the hash over a wrapped representation of the content, not the raw bytes themselves. Specifically, Git prepends the following header before hashing:

<type> <size>\0<content>

Only <content> corresponds to the original uploaded data. Therefore, the hash being verified is not that of the raw content.

This behavior is confirmed by the following commands:

$ sha1sum third-party/rust/crates/errno/0.3.14/BUCK
3873e6d99a2a6e71f404f903e6867e49272ff987  third-party/rust/crates/errno/0.3.14/BUCK

$ git hash-object -w third-party/rust/crates/errno/0.3.14/BUCK
5349b3b7fb470ed14e192cfab5a399f9f1ddc464

The API should compute and verify the SHA-1 hash over the raw content directly, rather than relying on Git's internal blob hash format.