fix(installer): reinstall when current version directory is incomplete

The same-version check now verifies that the binary (current/bin/vp.exe)
actually exists, not just that the current symlink points at the target
version. If the version directory is corrupted or partially deleted,
the installer performs a full reinstall instead of skipping to the
best-effort repair steps which cannot restore missing core files.

Author: fengmk2

crates/vite_installer/src/main.rs

@@ -127,7 +127,11 @@ async fn do_install(
     let target_version =
         registry::resolve_version_string(version_or_tag, opts.registry.as_deref()).await?;
 
-    let same_version = current_version.as_deref() == Some(target_version.as_str());
+    // Same version only if the binary is intact — a corrupted install needs a full reinstall
+    let same_version = current_version.as_deref() == Some(target_version.as_str())
+        && tokio::fs::try_exists(install_dir.join("current").join("bin").join(VP_BINARY_NAME))
+            .await
+            .unwrap_or(false);
 
     if same_version {
         if !opts.quiet {