fix frozen time bounds on the recordings API (#24121)

`after` and `before` defaulted to `datetime.now()` in the function signature, so they were evaluated once at import. Requests that omitted them got a window ending at process start. They now resolve in the handler.

frigate/api/record.py

@@ -358,10 +358,13 @@ async def recordings_coverage(
 @router.get("/{camera_name}/recordings", dependencies=[Depends(require_camera_access)])
 async def recordings(
     camera_name: str,
-    after: float = (datetime.now() - timedelta(hours=1)).timestamp(),
-    before: float = datetime.now().timestamp(),
+    after: float | None = None,
+    before: float | None = None,
 ):
     """Return specific camera recordings between the given 'after'/'end' times. If not provided the last hour will be used"""
+    now = datetime.now()
+    after = after if after is not None else (now - timedelta(hours=1)).timestamp()
+    before = before if before is not None else now.timestamp()
     recordings = (
         Recordings.select(
             Recordings.id,