Adds a ConvertTo-LongPath helper to install.ps1 that expands a Windows 8.3
short path (e.g. C:\Users\FIRST~1.LAS) back to its long form via
Scripting.FileSystemObject. Paths without a "~<digit>" component are returned
unchanged (no COM round-trip), and any COM failure falls back to the input.
Adds an AST-loaded unit test that exercises the helper without executing the
installer body (pass-through, null/empty, and graceful fallback).
