feat(platform): add audit logs and activity feed

backend/hermes/app/schemas/audit.py

@@ -0,0 +1,39 @@
+from datetime import datetime
+from typing import Any
+
+from pydantic import BaseModel, ConfigDict
+
+
+class AuditLogResponse(BaseModel):
+    id: int
+    actor_user_id: int | None
+    actor_username: str
+    action: str
+    entity_type: str
+    entity_id: int | None
+    entity_label: str
+    ip_address: str
+    user_agent: str
+    before_data: Any = None
+    after_data: Any = None
+    metadata_data: Any = None
+    created_at: datetime
+
+    model_config = ConfigDict(from_attributes=True)
+
+
+class AuditLogListResponse(BaseModel):
+    items: list[AuditLogResponse]
+    total: int
+    page: int
+    page_size: int
+
+
+class ActivityFeedItem(BaseModel):
+    id: int
+    title: str
+    description: str
+    actor: str
+    entity_type: str
+    entity_id: int | None
+    created_at: datetime