q4_K_M quantization

Qwen3 4B matches Qwen2.5 7B case for case at half the cold start

Across 20 paired writing-correction cases on Ollama for Windows, the two models succeeded on the same 18 and failed on the same 2, while the 4B averaged 23.99 seconds of cold start against 54.37. That reorders local shortlisting.