common : respect specified tag, only fallback when tag is empty (#21413)

Signed-off-by: Adrien Gallouët <angt@huggingface.co>

common/download.cpp

@@ -596,11 +596,14 @@ static hf_cache::hf_file find_best_model(const hf_cache::hf_files & files,
         }
     }
 
+    // fallback to first available model only if tag is empty
+    if (tag.empty()) {
         for (const auto & f : files) {
             if (gguf_filename_is_model(f.path)) {
                 return f;
             }
         }
+    }
 
     return {};
 }