Gitea local code execution through writable Git hooks

Gitea creates server-side Git hook directories and scripts with mode 0777 and relies on the process umask to restrict access. With a permissive umask such as 0000 or 0002, another local user who can reach the repository storage may modify a hook or add an executable to a writable hook directory. A later Git operation can execute that file as the Gitea service account.