feat: support Home Assistant clean_area (room cleaning) for vacuum

[eduardobittencourt]

Summary

Adds support for Home Assistant core's native vacuum.clean_area service (the CLEAN_AREA feature, available in recent HA core). Users can clean specific rooms by selecting Home Assistant areas; HA maps those areas to the vacuum's rooms (segments) and the integration tells the robot to clean them.

This complements send_command / app_segment_clean (e.g. #1702): it wires room cleaning into HA's first-class areas UI instead of requiring raw room ids in automations.

How it works

HA core does the heavy lifting (the area↔segment mapping dialog + storage, and the vacuum.clean_area service). An integration only needs to:

1. set VacuumEntityFeature.CLEAN_AREA,
2. implement async_get_segments() → the device's rooms,
3. implement async_clean_segments(segment_ids) → start a room sweep.

This PR maps those onto the standard MIoT spec:

• async_get_segments() reads the room-information property ({"rooms":[{"id","name"}]}) → Segment(id, name).
• async_clean_segments() calls the start-vacuum-room-sweep action with vacuum-room-ids as a JSON array string (e.g. "[3, 10]").

Everything is capability-gated and version-guarded:

• CLEAN_AREA is enabled only when the device exposes both room-information and start-vacuum-room-sweep, so models without room cleaning are unaffected.
• Segment / CLEAN_AREA are imported behind try/except + hasattr, so older HA core keeps working unchanged.

Changes

• vacuum.py: capture the room property/action, enable CLEAN_AREA, add async_get_segments / async_clean_segments.
• miot/specs/specv2entity.py: route room-information and start-vacuum-room-sweep into the vacuum entity (as optional).

Test plan

Tested on xiaomi.vacuum.d102gl (HA core 2026.6):

• vacuum.clean_area lists the vacuum (CLEAN_AREA feature present).
• The HA area → room mapping dialog shows the robot's rooms (async_get_segments).
• Cleaning one area (Living room) cleans that room.
• Cleaning multiple areas (Living room + Kitchen) cleans both — payload "[3, 10]".
• pylint clean on the changed lines (no new warnings).

Notes

• The vacuum-room-ids string is firmware-defined (the spec only types it as str). The JSON array form works on the d102gl and matches the app_segment_clean payload in feat: add complete support of S40 pro vacuum #1702; confirmation on other models is welcome.
• Could be extended to zone cleaning (start-zone-sweep) the same way.

[CLAassistant]

All committers have signed the CLA.

[gzamboni]

@SusanPhevos this is a long waited feature to vacuum robots. This PR gonna be a quality of life update for real.