tool-call: support Command R7B (+ return tool_plan "thoughts" in API) (#11585)

* `tool-call`: support Command R7B (w/ tool_plan return)

* `tool-call`: cleaner preservation of tokens + warn when likely bad chat template override

* `tool-call`: test cleanup / handle lazy grammar triggers

examples/server/utils.hpp

@@ -662,6 +662,7 @@ static json oaicompat_completion_params_parse(
             });
         }
         llama_params["grammar_triggers"] = grammar_triggers;
+        llama_params["preserved_tokens"] = chat_params.preserved_tokens;
         for (const auto & stop : chat_params.additional_stops) {
             llama_params["stop"].push_back(stop);
         }