fix: Don't limit tempalte expansion check to jinja

With the use_jinja check, non-jinja models would enable thinking and always
fail assistant prefill

Branch: gabe-l-hart/thinking-model-disabled-agent-prefill

Signed-off-by: Gabe Goodhart <[email protected]>

Author: gabe-l-hart

tools/server/server.cpp

@@ -2181,7 +2181,7 @@ struct server_context {
         // 1. It's not explicitly disabled (reasoning_budget == 0)
         // 2. The chat template supports it
         bool enable_thinking = params_base.reasoning_budget != 0;
-        if (enable_thinking && params_base.use_jinja) {
+        if (enable_thinking) {
             common_chat_templates_inputs dummy_inputs;
             common_chat_msg msg;
             msg.role = "user";