Drop trailing arguments when writing shebangs (#14519)
## Summary
You can see in pip that they read the full first line, then replace it
with the rewritten shebang, thereby dropping any trailing arguments on
the shebang:
https://github.com/pypa/pip/blob/65da0ff5349297da64ccadb4dd22ab41185ea0b9/src/pip/_internal/operations/install/wheel.py#L94
In contrast, we currently retain them, but write them _after_ the
shebang, which is wrong.
Closes https://github.com/astral-sh/uv/issues/14470.
