fix: use pwsh instead of powershell for Windows install

Windows PowerShell 5.1 (powershell.exe) doesn't support 3+ arguments
to Join-Path, which the install script uses. PowerShell 7 (pwsh) is
available on GitHub Actions runners and handles this correctly.

Author: fengmk2

CLAUDE.md

@@ -34,7 +34,7 @@ vp run fmt
 vp run fmt:check
 ```
 
-**Important:** Always run `vp run build` after code changes - the `dist/index.mjs` must be committed.
+**Important:** Always run `vp fmt` and `vp run build` before committing - the `dist/index.mjs` must be committed.
 
 ## Architecture
 

dist/index.mjs

@@ -15,7 +15,11 @@ export async function installVitePlus(inputs: Inputs): Promise<void> {
   let exitCode: number;
 
   if (process.platform === "win32") {
-    exitCode = await exec("powershell", ["-Command", `& ([scriptblock]::Create((irm ${INSTALL_URL_PS1})))`], { env });
+    exitCode = await exec(
+      "pwsh",
+      ["-Command", `& ([scriptblock]::Create((irm ${INSTALL_URL_PS1})))`],
+      { env },
+    );
   } else {
     exitCode = await exec("bash", ["-c", `curl -fsSL ${INSTALL_URL_SH} | bash`], { env });
   }