优化传感器布置算法，修复数据库更新逻辑

app/infra/db/timescaledb/repositories/scada.py

@@ -89,12 +89,17 @@ class ScadaRepository:
         if field not in valid_fields:
             raise ValueError(f"Invalid field: {field}")
 
-        query = sql.SQL(
+        update_query = sql.SQL(
             "UPDATE scada.scada_data SET {} = %s WHERE time = %s AND device_id = %s"
         ).format(sql.Identifier(field))
+        insert_query = sql.SQL(
+            "INSERT INTO scada.scada_data (time, device_id, {}) VALUES (%s, %s, %s)"
+        ).format(sql.Identifier(field))
 
         async with conn.cursor() as cur:
-            await cur.execute(query, (value, time, device_id))
+            await cur.execute(update_query, (value, time, device_id))
+            if cur.rowcount == 0:
+                await cur.execute(insert_query, (time, device_id, value))
 
     @staticmethod
     async def delete_scada_by_id_time_range(