修复丢失的api；重新规划api结构

app/api/v1/endpoints/network/regions.py

@@ -231,3 +231,15 @@ async def fastapi_generate_virtual_district(
 ) -> ChangeSet:
     props = await req.json()
     return generate_virtual_district(network, props["centers"], inflate_delta)
+
+@router.get("/calculatedistrictmeteringareafornodes/")
+async def fastapi_calculate_district_metering_area_for_nodes(
+    network: str, req: Request
+) -> list[list[str]]:
+    props = await req.json()
+    nodes = props["nodes"]
+    part_count = props["part_count"]
+    part_type = props["part_type"]
+    return calculate_district_metering_area_for_nodes(
+        network, nodes, part_count, part_type
+    )