Initial commit: tuned multi-model llama.cpp stack

- 5 models: SmolLM3-3B, Gemma4-E2B/E4B, Qwen3-4B, Qwen3.5-9B
- TurboQuant image (FORCE_MMQ): +6-11% free speed on Turing GPUs
- Bigctx profiles (-nkvo KV in RAM): 2-16x context gain
- turbo2 KV: 2x smaller, benchmarked against PPL quality gate
- Per-model env files with justified parameters
- kv_quant_test.sh + cpu_ctx_test.sh benchmark scripts
- docs/FINDINGS.md: surprises, pitfalls, recommendations
- docs/ARCHITECTURE.md: compose + test script design

envs/.env.qwen3-4b-bigctx

@@ -0,0 +1,24 @@
+# ==============================================================================
+# Qwen3-4B Q4_K_M — bigctx variant (KV in RAM via -nkvo)
+# Benchmarked 2026-05-06: -nkvo max ctx=24576 (+8K vs pure-GPU 16384)
+# Baseline TG: ~39 t/s (empty KV).
+# Use this profile when you need >16K context; otherwise use qwen3-4b.
+# ==============================================================================
+
+MODEL_FILE=Qwen3-4B-Q4_K_M.gguf
+
+N_GPU_LAYERS=99
+CTX_SIZE=24576
+
+THREADS=6
+THREADS_BATCH=6
+
+BATCH_SIZE=512
+UBATCH_SIZE=256
+
+CACHE_TYPE_K=q4_0
+CACHE_TYPE_V=q4_0
+
+PARALLEL=1
+
+EXTRA_ARGS=--flash-attn on --mmap --no-kv-offload