Update content type validation in ServeHTTP method for Steam files

- Changed expected Content-Type from "application/octet-stream" to "application/x-steam-chunk" to align with Steam's file specifications.
- Enhanced warning message for unexpected content types to provide clearer context for debugging.

steamcache/steamcache.go

@@ -502,13 +502,13 @@ func (sc *SteamCache) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 			return
 		}
 
-		// Method 2: Content-Type Validation (Steam files should be binary)
+		// Method 2: Content-Type Validation (Steam files should be application/x-steam-chunk)
 		contentType := resp.Header.Get("Content-Type")
-		if contentType != "" && !strings.Contains(contentType, "application/octet-stream") {
+		if contentType != "" && !strings.Contains(contentType, "application/x-steam-chunk") {
 			logger.Logger.Warn().
 				Str("url", req.URL.String()).
 				Str("content_type", contentType).
-				Msg("Unexpected content type from Steam")
+				Msg("Unexpected content type from Steam - expected application/x-steam-chunk")
 		}
 
 		// Method 3: Content-Length Validation