feat: expose full motion video list for dual-lens devices

[quicksilver2000]

Expose the full list of thirdPartPlayUnits as a new attribute motion_video_list in get_alarm_eventlist(), so devices with dual-lens cameras (e.g. M30 Pro door lock) can access both streams.

Backward compatible: motion_video_latest is unchanged.

Fixes #2929

[quicksilver2000]

Title: feat: expose full motion video list for dual-lens devices

Summary

Expose the full list of thirdPartPlayUnits as a new state attribute motion_video_list in get_alarm_eventlist(), so devices with dual-lens cameras (e.g. Xiaomi Smart Door Lock M30 Pro, xiaomi.lock.m30fc) can access both video streams that belong to the same doorbell event.

Background

When the doorbell is pressed, the M30 Pro records two video streams at the same moment:

Lens	Resolution	Content
Upper lens	2048x1536	Face / close-up
Lower lens	1920x1080	Wide view of the door area

In the Mi Home app these two streams are merged into one full picture. However, the current integration only exposes the first event (motion_video_latest), so only a single lens is accessible.

The API returns two thirdPartPlayUnits with createTime differing by only ~140 ms (the two lenses of the same event):

[
  {"fileId": "...848629760", "createTime": 1787568629603, "eventType": "IgnoreEvent", ...},
  {"fileId": "...674565632", "createTime": 1787568629463, "eventType": "Stay:Face", ...}
]

The second one is currently discarded.

Changes

• Add a new attribute motion_video_list containing the full list of events.
• Keep motion_video_latest unchanged (backward compatible).
• Generic design — does not assume the first two entries belong to the same event (single-lens devices and multi-event responses are unaffected).

Testing

• Device: Xiaomi Smart Door Lock M30 Pro (xiaomi.lock.m30fc)
• Verified motion_video_list contains both lens records, createTime differ by ~140 ms
• Both m3u8 streams are downloadable

Related issue

Fixes #2929