[core] Defer stdlib imports out of the upload and logs fast path (#18105)

esphome/storage_json.py

@@ -1,11 +1,11 @@
 from __future__ import annotations
 
 import binascii
-from datetime import datetime
 import json
 import logging
 import os
 from pathlib import Path
+from typing import TYPE_CHECKING
 
 from esphome import const
 from esphome.const import (
@@ -24,6 +24,9 @@ from esphome.core import CORE, EsphomeError, Version
 from esphome.helpers import write_file_if_changed
 from esphome.types import CoreType
 
+if TYPE_CHECKING:
+    from datetime import datetime
+
 _LOGGER = logging.getLogger(__name__)
 
 
@@ -372,6 +375,10 @@ class EsphomeStorageJSON:
 
     @property
     def last_update_check(self) -> datetime | None:
+        # Deferred: this module is on the upload/logs fast path; only the
+        # dashboard's update check touches these accessors.
+        from datetime import datetime
+
         try:
             # Stored format is naive ISO without %z; preserved for backward compat.
             return datetime.strptime(  # noqa: DTZ007