Ignore Ctrl-C signals in uv run and uv tool run (#5395)

## Summary

This is a bit simpler than #5333, but seems to work in my testing on
macOS and Windows. It's based on implementations that I found in
[Pixi](36f1bb297d/src/cli/exec.rs (L99))
and
[Wasmer](49e60af8df/lib/wasix/src/state/builder.rs (L1058)).

Closes https://github.com/astral-sh/uv/issues/5257.

## Test Plan

On both macOS and Windows:

- `cargo run -- tool run --from jupyterlab jupyter-lab` -- hit Ctrl-C;
verify that the process exits and the terminal is left in a good state.
- `cargo run -- run python` -- hit Ctrl-C; verify that the process does
_not_ exit, but does on Ctrl-D.

crates/uv/src/commands/project/run.rs

@@ -471,6 +471,12 @@ pub(crate) async fn run(
             command.executable().to_string_lossy()
         )
     })?;
+
+    // Ignore signals in the parent process, deferring them to the child. This is safe as long as
+    // the command is the last thing that runs in this process; otherwise, we'd need to restore the
+    // signal handlers after the command completes.
+    let _handler = tokio::spawn(async { while tokio::signal::ctrl_c().await.is_ok() {} });
+
     let status = handle.wait().await.context("Child process disappeared")?;
 
     // Exit based on the result of the command

crates/uv/src/commands/tool/run.rs

@@ -185,6 +185,11 @@ pub(crate) async fn run(
     }
     .with_context(|| format!("Failed to spawn: `{}`", executable.to_string_lossy()))?;
 
+    // Ignore signals in the parent process, deferring them to the child. This is safe as long as
+    // the command is the last thing that runs in this process; otherwise, we'd need to restore the
+    // signal handlers after the command completes.
+    let _handler = tokio::spawn(async { while tokio::signal::ctrl_c().await.is_ok() {} });
+
     let status = handle.wait().await.context("Child process disappeared")?;
 
     // Exit based on the result of the command