Add a response template

Same as https://huggingface.co/allenai/AstaBrief_8B/discussions/1 (the tokenizer config is identical).

This PR adds a `response_template` to `tokenizer_config.json`, so `tokenizer.parse_response(...)` turns a generation back into a message with `reasoning_content`, `content` and `tool_calls` (transformers >= 5.13). It's the Qwen3 one, since the chat template is the Qwen3 one.

tokenizer_config.json

@@ -235,5 +235,32 @@
   "pad_token": "<|endoftext|>",
   "split_special_tokens": false,
   "tokenizer_class": "Qwen2Tokenizer",
-  "unk_token": null
+  "unk_token": null,
+  "response_template": {
+    "defaults": {
+      "role": "assistant"
+    },
+    "start_anchor": "<|im_start|>assistant\n",
+    "fields": {
+      "reasoning_content": {
+        "open": "<think>",
+        "close_pattern": "</think>\\s*",
+        "content": "text"
+      },
+      "tool_calls": {
+        "open": "<tool_call>",
+        "close_pattern": "</tool_call>\\s*",
+        "repeats": true,
+        "content": "json",
+        "transform": {
+          "type": "function",
+          "function": "{content}"
+        }
+      },
+      "content": {
+        "close_pattern": "<\\|im_end\\|>\\s*",
+        "content": "text"
+      }
+    }
+  }
 }