fix(e2e): use exec to improve SIGINT delivery on Unix

On Unix systems, running commands through a shell creates a process
chain (sh → vite → node) which makes SIGINT delivery unreliable.
Using 'exec' replaces the shell with the actual command, reducing
the process hierarchy and making signal propagation work correctly.

This fixes the ctrl-c-interruption test on Ubuntu where the SIGINT
was not reaching the Node.js process, causing timeouts instead of
graceful shutdowns.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: branchseer

crates/vite_task_bin/tests/e2e_snapshots/main.rs

@@ -175,8 +175,15 @@ async fn run_case_inner(tmpdir: &AbsolutePath, fixture_path: &Path, fixture_name
         let mut e2e_outputs = String::new();
         for step in e2e.steps {
             let mut cmd = Command::new(&shell_exe);
+            // On Unix, use exec to replace the shell with the command, reducing process hierarchy
+            // This makes Ctrl+C signal propagation more reliable
+            #[cfg(unix)]
+            let cmd_str = format!("exec {}", step.cmd());
+            #[cfg(not(unix))]
+            let cmd_str = step.cmd().to_string();
+
             cmd.arg("-c")
-                .arg(step.cmd())
+                .arg(cmd_str)
                 .env_clear()
                 .env("PATH", &e2e_env_path)
                 .env("NO_COLOR", "1")