Fix Stop-A validation config: system vllm, cap max-model-len

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

configs/examples/dash0_qwen30b_a3b_stopA_fulldata.json

@@ -14,7 +14,7 @@
   "engine": {
     "engine_name": "vllm",
     "engine_version": "0.20.0",
-    "exec_path": "/tmp/wjh/venvs/vllm-0.20.0-cu129/bin/vllm",
+    "exec_path": "/usr/local/bin/vllm",
     "cwd": "/home/admin/cpfs/wjh/aituner/aituner",
     "host": "127.0.0.1",
     "port": 18230,
@@ -33,7 +33,11 @@
     "base_flags": {
       "host": "127.0.0.1",
       "port": 18230,
-      "served-model-name": "qwen3-30b-a3b-community"
+      "served-model-name": "qwen3-30b-a3b-community",
+      "gpu-memory-utilization": 0.9,
+      "max-model-len": 16384,
+      "trust-remote-code": true,
+      "enable-prefix-caching": true
     },
     "tunable_envs": [],
     "tunable_flags": [
@@ -123,7 +127,7 @@
     "low": 0.0,
     "high": 0.125,
     "tolerance": 0.001,
-    "max_probes": 5,
+    "max_probes": 4,
     "sample_seed": 20260325
   },
   "llm": {