Fix Windows path separator issue using PathBuf (#482)

* Update mod.rs

The following code uses a separator that is not compatible with Windows:

format!("{}/{}", file_config.path.clone(), rustfs_config::DEFAULT_SINK_FILE_LOG_FILE)


Change it to the following code:


std::path::Path::new(&file_config.path)
    .join(rustfs_config::DEFAULT_SINK_FILE_LOG_FILE)
    .to_string_lossy()
    .to_string()

* Replaced format! macro with PathBuf::join to fix path separator issue on Windows.Tested on Windows 10 with Rust 1.85.0, paths now correctly use \ separator.

crates/obs/src/sinks/mod.rs

@@ -79,7 +79,10 @@ pub async fn create_sinks(config: &AppConfig) -> Vec<Arc<dyn Sink>> {
             SinkConfig::File(file_config) => {
                 tracing::debug!("FileSink: Using path: {}", file_config.path);
                 match file::FileSink::new(
-                    format!("{}/{}", file_config.path.clone(), rustfs_config::DEFAULT_SINK_FILE_LOG_FILE),
+                    std::path::Path::new(&file_config.path)
+                        .join(rustfs_config::DEFAULT_SINK_FILE_LOG_FILE)
+                        .to_string_lossy()
+                        .to_string(),
                     file_config
                         .buffer_size
                         .unwrap_or(rustfs_config::observability::DEFAULT_SINKS_FILE_BUFFER_SIZE),