chore: 忽略 skill_evolution.json 运行时文件

前端 PUT /api/curator/config 会把 per-user 覆盖写到
backend/skill_evolution.json（全局 fallback），属于运行时
数据不该入库。

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.gitignore

@@ -71,3 +71,6 @@ hermes-agent-main/
 skills/*
 
 offline-backend-20260512/backend/.deer-flow/*
+
+# Per-user skill_evolution overrides — runtime data written by the API
+offline-backend-20260512/backend/skill_evolution.json