Use current platform for binary extension, not target platform

The platform option specifies the target platform for the binary being
downloaded, but the binary is executed on the current platform. Use WIN32
constant for determining the extension since that's where execution happens.

Example: On Windows with platform: 'linux', generates binary-linux-arm64.cmd
which can be executed as a script wrapping the actual binary.

Author: jdalton

registry/src/lib/dlx-binary.ts

@@ -250,8 +250,8 @@ export async function dlxBinary(
   const cacheDir = getDlxCachePath()
   const cacheKey = generateCacheKey(url)
   const cacheEntryDir = path.join(cacheDir, cacheKey)
-  // Use target platform for extension when generating binary name.
-  const ext = targetPlatform === 'win32' ? EXT_CMD : ''
+  // Use current platform for extension since we'll execute on current platform.
+  const ext = WIN32 ? EXT_CMD : ''
   const binaryName = name || `binary-${targetPlatform}-${arch}${ext}`
   const binaryPath = normalizePath(path.join(cacheEntryDir, binaryName))