feat: Phase 7 — add validation field to decision log schema

Add "validation" key to _log_decision() entry dict in deepseek_brain.py.
Captures result.get("validation") (None if validator disabled)
for R1-14B output preservation and future analysis.

src/commander_ai_lab/sim/deepseek_brain.py

@@ -784,7 +784,8 @@ class DeepSeekBrain:
                 "source": result.get("source"),
                 "latency_ms": result.get("latency_ms"),
             },
-            "game_result": None,
+            "validation": result.get("validation"),
+          "game_result": None,
         }
         self._decision_log.append(entry)