Ollama serves Qwen3 thinking inside the content field as <think>...</think>
blocks rather than in the API-level reasoning_content field. This means
_has_structured was False for these responses, so an empty-looking reply
after a tool call triggered the nudge instead of the prefill continuation,
causing a double-response loop.
Fix: detect <think>/<thinking>/<reasoning> in final_response and:
1. Skip the nudge when thinking is present (model is still reasoning)
2. Include _has_inline_thinking in _has_structured so prefill kicks in
