Propagate URL errors in verbatim parsing (#3720)
## Summary
Closes https://github.com/astral-sh/uv/issues/3715.
## Test Plan
```
❯ echo "/../test" | cargo run pip compile -
error: Couldn't parse requirement in `-` at position 0
Caused by: path could not be normalized: /../test
/../test
^^^^^^^^
❯ echo "-e /../test" | cargo run pip compile -
error: Invalid URL in `-`: `/../test`
Caused by: path could not be normalized: /../test
Caused by: cannot normalize a relative path beyond the base directory
```
