feat(km): add full corpus asset taxonomy readback

apps/api/src/models/knowledge.py

@@ -122,11 +122,18 @@ class CategoryCount(BaseModel):
     count: int
 
 
+class KnowledgeAssetTaxonomyCount(BaseModel):
+    """AI 自動化資產維度統計"""
+    key: str
+    count: int
+
+
 class KnowledgeListResponse(BaseModel):
     """列表回應"""
     items: list[KnowledgeEntry]
     total: int
     categories: list[CategoryCount] = Field(default_factory=list)
+    asset_taxonomy: list[KnowledgeAssetTaxonomyCount] = Field(default_factory=list)
     readback_status: str = "ready"
     operator_stage: str | None = None
     next_step: str | None = None