fix(azure_blob): handle root path listing

[Kukmoon]

Description

Fix Azure Blob Storage root directory listing.

Problem

When the Azure Blob Storage driver receives the root path, dir.GetPath() can be an empty string. The Azure Blob Storage container contained blobs, including a previously uploaded file, but the root directory was displayed as empty in Alist.

The previous implementation always called ensureTrailingSlash():

prefix := ensureTrailingSlash(dir.GetPath())

This converted the root path from "" to "/".

For Azure Blob Storage listing, using "/" as the root prefix does not match blob names that do not begin with /, resulting in an empty root directory listing.

The Azure Blob Storage container did contain files:

Fix

Handle the root path explicitly:

prefix := dir.GetPath()
if prefix == "" || prefix == "/" {
    prefix = ""
} else {
    prefix = ensureTrailingSlash(prefix)
}

This preserves an empty prefix for the root directory while continuing to append / for non-root directories.

Testing

• gofmt passed
• git diff --check passed
• Project compiled successfully
• Verified Azure Blob Storage root listing
• Verified entering subdirectories
• Verified uploading files into a subdirectory
• Verified uploaded files can be listed normally

The final result: