## Why
`AbsolutePathBuf::relative_to_current_dir` previously read the current directory even for absolute paths, causing resolution to fail if the current directory had been deleted.
## What changed
Route absolute inputs through `from_absolute_path` without querying the current directory. Relative inputs continue to resolve against the current directory.
## Testing
Extend the Unix regression test to verify that `relative_to_current_dir` succeeds with a deleted current directory and produces the same normalized path as `from_absolute_path`.
GitOrigin-RevId: 6bc6cb43d9f4d57359639708c4d30524d89cfa92