Merge branch 'upstream' into concedo_experimental

# Conflicts:
#	.github/workflows/docker.yml
#	docs/ops.md
#	docs/ops/Metal.csv
#	ggml/CMakeLists.txt
#	ggml/src/ggml-sycl/CMakeLists.txt
#	grammars/README.md
#	models/templates/llama-cpp-deepseek-r1.jinja
#	scripts/sync-ggml.last
#	tests/test-chat.cpp

common/chat.cpp

@@ -320,7 +320,7 @@ json common_chat_msgs_to_json_oaicompat(const std::vector<common_chat_msg> & msg
                 }
             }
         } else {
-            jmsg["content"] = json(); // null
+            jmsg["content"] = "";
         }
         if (!msg.reasoning_content.empty()) {
             jmsg["reasoning_content"] = msg.reasoning_content;
@@ -381,8 +381,8 @@ std::vector<common_chat_tool> common_chat_tools_parse_oaicompat(const json & too
                 const auto & function = tool.at("function");
                 result.push_back({
                     /* .name = */ function.at("name"),
-                    /* .description = */ function.at("description"),
-                    /* .parameters = */ function.at("parameters").dump(),
+                    /* .description = */ function.value("description", ""),
+                    /* .parameters = */ function.value("parameters", json::object()).dump(),
                 });
             }
         }