Fix accessory device registration on newer Home Assistant

[aderusha]

Fixes #17.

Problem

On HA 2026.9.3, accessory firmware entities can fail to register because the deprecated via_device path raises MissingIntegrationFrame / RuntimeError. A Fire Safety Set v1.5 detected by an S1 consequently has no device in HA, since its firmware entity is its only entity. Related HA report: home-assistant/core#180469.

Change

Register the laser device before platform setup using the existing laser entity metadata, retain its registry ID on the coordinator, and supply via_device_id from both accessory entity classes. Feature-detect the DeviceInfo field to retain legacy linking on older supported HA versions. Existing device identifiers and entity unique IDs remain unchanged.

Validation

• Three focused regression tests pass against HA 2026.9.3's installed libraries: firmware-only accessory registration metadata, regular accessory parent linking, and legacy API fallback.
• ha core check passes.
• Verified on a live S1 after restart: Fire Safety Set v1.5 now registers as a device linked to the S1, firmware V40.203.002.3224.01B01 is reported, and the Smart Air Assist firmware entity also loads. The S1 continues reporting idle. No accessory via_device warnings or update-entity registration errors appeared in the post-restart logs.

Run the regression tests from the repository root in an environment with Home Assistant installed:

python -m unittest discover -s tests