refactor(plan): extract powershell prefix flags to const

Address review feedback on #345:
- Extract the 5 fixed PowerShell prefix flags to a `const POWERSHELL_PREFIX`
- Build `new_args` via iterator chain instead of manual Vec pushes
- Drop the no-op `let _ = (&program_path, &args);` on non-Windows

Author: fengmk2

crates/vite_task_plan/src/powershell.rs

@@ -35,7 +35,6 @@ pub fn rewrite_cmd_shim_to_powershell(
 
     #[cfg(not(windows))]
     {
-        let _ = (&program_path, &args);
         (program_path, args)
     }
 }
@@ -47,6 +46,12 @@ mod imp {
     use vite_path::{AbsolutePath, AbsolutePathBuf};
     use vite_str::Str;
 
+    /// Fixed arguments prepended before the `.ps1` path. `-NoProfile`/`-NoLogo`
+    /// skip user profile loading; `-ExecutionPolicy Bypass` allows running the
+    /// unsigned shims that npm/pnpm install into `node_modules/.bin`.
+    const POWERSHELL_PREFIX: &[&str] =
+        &["-NoProfile", "-NoLogo", "-ExecutionPolicy", "Bypass", "-File"];
+
     /// Cached location of the PowerShell host used to run `.ps1` shims. Prefers
     /// cross-platform `pwsh.exe` when present, falling back to the Windows
     /// built-in `powershell.exe`. `None` means no host was found in PATH.
@@ -89,16 +94,15 @@ mod imp {
             ps1_str,
         );
 
-        let mut new_args: Vec<Str> = Vec::with_capacity(6 + args.len());
-        new_args.push(Str::from("-NoProfile"));
-        new_args.push(Str::from("-NoLogo"));
-        new_args.push(Str::from("-ExecutionPolicy"));
-        new_args.push(Str::from("Bypass"));
-        new_args.push(Str::from("-File"));
-        new_args.push(Str::from(ps1_str));
-        new_args.extend(args.iter().cloned());
+        let new_args: Arc<[Str]> = POWERSHELL_PREFIX
+            .iter()
+            .copied()
+            .map(Str::from)
+            .chain(std::iter::once(Str::from(ps1_str)))
+            .chain(args.iter().cloned())
+            .collect();
 
-        (Arc::clone(host), Arc::<[Str]>::from(new_args))
+        (Arc::clone(host), new_args)
     }
 }