Fix symlink traversal in task uploads

[LuoPengcheng12138]

Description

This PR closes a symlink-based escape in task file collection and upload:

• Task file listing now skips symlinks and validates real paths to ensure they stay inside the working directory.
• Electron’s file enumeration uses lstat + realpath to prevent recursive traversal through external links.
• sanitize_command() to validate ln -s will implement in Camel repo

What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

[4pmtong]

How about add a try-catch here to handle potential errors(e.g file doesn't exist, permission denied)

[LuoPengcheng12138]

Okay, but there's already a try-catch block wrapping the entire function, maybe adding another one here seems a bit redundant?

[4pmtong]

This really depends on the intended behavior:
Current approach (fail fast): Any file error stops the entire traversal
With inner try-catch (best effort): Skip problematic files and continue
What's your preference here? Should one bad file fail the entire upload, or should we skip it and continue with the rest?

[LuoPengcheng12138]

You are right~ we should skip it and continue with the rest.

[a7m-1st]

Thanks @LuoPengcheng12138 , can you add test cases for this? I have already added a comprehensive test suite for electron file mngmnt. LGTM though 👍

[Wendong-Fan]

thanks @LuoPengcheng12138 and @4pmtong !