Replace __import__('datetime') antipattern in health_check task

backend/app/tasks/health_check.py

@@ -32,9 +32,10 @@ from app.utils.runtime_state import (
 )
 
 if TYPE_CHECKING:  # pragma: no cover
-    from app.config import Settings
     from fastapi import FastAPI
 
+    from app.config import Settings
+
 log: structlog.stdlib.BoundLogger = structlog.get_logger()
 
 
@@ -53,7 +54,7 @@ HEALTH_CHECK_INTERVAL: int = 30
 _ACTIVATION_CRASH_WINDOW: int = 60
 
 
-async def _run_probe_with_resources(settings: "Settings", runtime_state: RuntimeState) -> None:
+async def _run_probe_with_resources(settings: Settings, runtime_state: RuntimeState) -> None:
     """Probe fail2ban and cache the result on the runtime state.
 
     Args:
@@ -162,9 +163,7 @@ def register(app: FastAPI) -> None:
         id="health_check",
         replace_existing=True,
         # Fire immediately on startup too, so the UI isn't dark for 30 s.
-        next_run_time=__import__("datetime").datetime.now(
+        next_run_time=datetime.datetime.now(tz=datetime.UTC),
-            tz=__import__("datetime").timezone.utc
-        ),
     )
     log.info(
         "health_check_scheduled",