fix: Allow firmware version as an optional field

[allenporter]

This field may not be returned by the API, in particular when the device is offline.

2025-12-14 18:09:25.550 ERROR (MainThread) [roborock.data.containers] Failed to convert devices with value [{'duid': 'yyyyyy', 'name': 'S6 Pure', 'localKey': 'xxxxxx', 'productId': 'zzzzzz', 'activeTime': NNNNNNN, 'timeZoneId': 'Europe/Moscow', 'iconUrl': '', 'share': False, 'online': False, 'pv': '1.0', 'tuyaMigrated': False, 'extra': '{}', 'deviceStatus': {}, 'silentOtaSwitch': False, 'f': False}] to type list[roborock.data.containers.HomeDataDevice]
Traceback (most recent call last):
  File "/usr/local/lib/python3.13/site-packages/roborock/data/containers.py", line 122, in from_dict
    result[key] = RoborockBase._convert_to_class_obj(field_type, value)
                  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.13/site-packages/roborock/data/containers.py", line 73, in _convert_to_class_obj
    return [RoborockBase._convert_to_class_obj(sub_type, obj) for obj in value]
            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.13/site-packages/roborock/data/containers.py", line 81, in _convert_to_class_obj
    return class_type.from_dict(value)
           ~~~~~~~~~~~~~~~~~~~~^^^^^^^
  File "/usr/local/lib/python3.13/site-packages/roborock/data/containers.py", line 127, in from_dict
    return cls(**result)
TypeError: HomeDataDevice.__init__() missing 1 required positional argument: 'fv'

Issue home-assistant/core#158918

[Copilot]

Pull request overview

This PR fixes a deserialization error that occurs when the Roborock API returns device data without a firmware version field, which typically happens when a device is offline. The change makes the fv (firmware version) field optional in the HomeDataDevice class.

Key Changes

• Made the fv field optional by adding a default value of None and moving it after required fields in the HomeDataDevice dataclass
• Updated test snapshots to reflect the field reordering in serialized output

Reviewed changes

Copilot reviewed 1 out of 2 changed files in this pull request and generated 1 comment.

File	Description
roborock/data/containers.py	Changed fv field from required to optional with default None, moved after product_id to maintain proper dataclass field ordering
tests/devices/snapshots/test_file_cache.ambr	Updated snapshot expectations to reflect fv field position change in serialized HomeDataDevice objects

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[Lash-L]

unexpected! definitely fine with this being option as we don't use it anyways in the library. We might use it on the HA side though. So this may require a change to check if it is None.