v0.3.19

• Context fitting with fine-tunes that ship their own chat template: when the tokenizer directory contains
  chat_template.jinja, the proxy now counts the prompt with that template (sandboxed Jinja, [exact] extra) instead
  of the built-in Qwen rendering. A Tiel/Sharp setup was under-counting by a few hundred tokens and sent requests the
  engine rejected (#28, #43, #44). Startup reports template=pack or builtin-qwen; on the stock Qwen3.8 pack the two
  counts are identical. Prompts that leave no room to answer are refused locally; a recognised engine context
  rejection is retried once with smaller output limits. Short stderr summaries of key events (window guard, clamps,
  masking, segment switches) with request phase labels; client disconnects no longer print a BrokenPipe traceback.
  Pack-template mode is text-only: requests with images are refused explicitly.
• A single fresh tool result that leaves no room for an answer is now archived behind the usual recall placeholder
  (only when recall is exposed and only if this restores a useful answer budget), instead of the request being
  forwarded with max_tokens clamped to 1. If nothing fits, the proxy returns an explicit context error (#40, #42).
• Tests: zstd fixtures no longer depend on the interpreter's sitecustomize (fixes 7 failures on Ubuntu with
  Python 3.14) (#39, #41).