[FEATURE] Support UNC paths (network shares)

[djdarcy]

Summary

Add support for UNC paths like \server\share\folder\file.bin in path preservation operations.

Problem

Current path logic assumes drive-letter based paths (e.g., C:\, D:\). UNC paths have different structure:

• No drive letter
• Root is \server\share
• Relative path is everything after the share name

Proposed Solution

Path Parsing

\server\share\folder\file.bin
└── root ──┘ └─ relative ─┘

• Treat \server\share as the "drive" equivalent
• Extract \folder\file.bin as the relative path

Considerations

1. Network latency: Operations may be slow
2. Permissions: May require authentication
3. Availability: Network might disconnect mid-operation
4. Mixed paths: One local, one UNC - how to handle REL?

Future Work

• Warning when operating on network paths
• --allow-network flag to explicitly enable
• Progress indication for slow network operations

Analysis

See 2025-12-23__19-50-21__path-preservation-options-design.md for context.