feat: Variet Engine v1.0 + 5-model tuning complete

Phase 01 (LLM Tuning):
- Gemma4 26B: 74.65 t/s (fast)
- Qwen 35B: 61.62 t/s (balanced)
- Gemma4 31B: 16.0 t/s (deep-coder)
- Qwen 27B: 16.7 t/s (deep-logic)
- Qwen 122B: 8.95 t/s (ultra, GPU 1 only)

Phase 02 (API Engine):
- FastAPI reverse proxy on port 8000
- /engine/switch hot-swap with 503 protection
- config/engine_models.json as single source of truth
- Replaced 4 individual .bat files with unified engine

File cleanup:
- scripts/ 85 files -> 9 + _archive/
- Root .bat files -> _archive/

_archive/start_qwen_122b_api.bat

@@ -0,0 +1,10 @@
+@echo off
+echo =========================================================
+echo  Qwen3.5 122B-A10B API Server (MoE Optimized)
+echo  [INFO] --cpu-moe: Expert weights forced to CPU RAM
+echo  [INFO] -ngl 999: All attention layers on GPU
+echo  [INFO] -np 1: Single slot, -c 2048 minimal context
+echo =========================================================
+echo.
+llama_bin_run\llama-server.exe --model models\Q4_K_M\Qwen3.5-122B-A10B-Q4_K_M-00001-of-00003.gguf -ngl 999 --cpu-moe -c 2048 -np 1 -fa on --cache-type-k q4_0 --cache-type-v q4_0 -ub 256 -b 1024 -t 8 --mlock --prio 2 --port 8000 --host 0.0.0.0
+pause