* chat : strip trailing whitespace from parsed reasoning and content
Assisted-by: Claude Fable 5.1
* chat : stop qwen3-coder reasoning and content before template separators
Assisted-by: Claude
* tests : remove the Qwen parser case from the chat session tests
Assisted-by: Claude
* common : handle partial prefix until match at end of generation
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Co-authored-by: Zeshawn Zahid <zzshawnn@gmail.com>
Co-authored-by: Alde Rojas <hello@alde.dev>