feat(skills): enhance skills system with matching and evaluation

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

backend/app/agents/skills/metadata.py

@@ -20,6 +20,10 @@ class SkillMetadata:
     source_id: str = ""  # 来源 ID
     enabled: bool = True  # 是否启用
     tools: list[str] = field(default_factory=list)  # 关联的工具
+    status: str = "active"  # candidate/shadow/active/deprecated/retired
+    scope: list[str] = field(default_factory=list)
+    effectiveness: float | None = None
+    review_after: str | None = None
 
     def to_dict(self) -> dict[str, Any]:
         return {
@@ -35,6 +39,10 @@ class SkillMetadata:
             "source_id": self.source_id,
             "enabled": self.enabled,
             "tools": self.tools,
+            "status": self.status,
+            "scope": self.scope,
+            "effectiveness": self.effectiveness,
+            "review_after": self.review_after,
         }
 
     @classmethod