Fix backend bugs: password hash column rename, dynamic import, AuditLog response_model, websocket reference, missing exports, bcrypt version pin

backend/app/routers/admin.py

@@ -184,7 +184,7 @@ async def list_logs(
     ]
 
 
-@router.post("/audit", response_model=AuditLog)
+@router.post("/audit", response_model=dict)
 async def log_audit(
     action_type: str,
     target_user_id: Optional[int] = None,
@@ -210,4 +210,11 @@ async def log_audit(
     db.add(new_audit)
     await db.flush()
     
-    return AuditLog.model_validate(new_audit)
+    return {
+        "id": new_audit.id,
+        "admin_id": new_audit.admin_id,
+        "action_type": new_audit.action_type,
+        "target_user_id": new_audit.target_user_id,
+        "details": new_audit.details,
+        "timestamp": new_audit.timestamp,
+    }