fix: use 422 instead of 500 for metadata access failures

Use 422 Unprocessable Entity instead of 500 Internal Server Error
for metadata access failures, as it's more semantically correct.
The file exists and path is valid, but can't be processed due to
metadata access issues (permissions, locks, etc.).

Author: ish1416

crates/tauri/src/protocol/asset.rs

@@ -57,7 +57,7 @@ fn get_response(
   // Check if we have read permissions
   if let Err(e) = std::fs::metadata(&path) {
     log::error!("Failed to get metadata for {}: {}", path, e);
-    return resp.status(500).body(format!("Failed to access file metadata: {}", e).into_bytes().into()).map_err(Into::into);
+    return resp.status(422).body(format!("Failed to access file metadata: {}", e).into_bytes().into()).map_err(Into::into);
   }
 
   let (mut file, len, mime_type, read_bytes) = crate::async_runtime::safe_block_on(async move {