server-filesystem directory volume char with diff form #1033

Describe the bug
In windows OS, the Allowed directories params are converted into with lower volume letter(like d:\Dive\share), while in validatePath function, the normalizedReal is returned with upper volume letter(like D:\Dive\share), thus the isRealPathAllowed value is false, leading all the tool methods call fail.

To Reproduce
Steps to reproduce the behavior:
1.
d:\dev>npx -y @modelcontextprotocol/inspector npx -y @modelcontextprotocol/server-filesystem /dev/Dive/share
2. in the browser connect to the mcp and list tools and select "list directory", then input "/dev/Dive/share"

Expected behavior
when submit, error returns as :
Error: Parent directory does not exist: d:\dev\Dive with error: Error: Access denied - parent directory outside allowed directories

Logs
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Additional context
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