Fix via_device race in rainbird

[emontnemery]

Proposed change

Fix via_device race in rainbird, and specify the via device by device ID

Background:
The device specified as via device must be created before the device linking to it.
In addition, via_device is deprecated, more context in https://developers.home-assistant.io/blog/2026/07/21/device-registry-single-config-entry/

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Deprecation (breaking change to happen in the future)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue:
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• Link to developer documentation pull request:
• Link to frontend pull request:

Checklist

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[home-assistant]

Hey there @konikvranik, @allenporter, mind taking a look at this pull request as it has been labeled with an integration (rainbird) you are listed as a code owner for? Thanks!

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[Copilot]

Pull request overview

Fixes Rain Bird zone-to-controller device linking by registering the controller before platform setup.

Changes:

• Pre-registers the controller device.
• Links zone devices using via_device_id.
• Adds linkage and migration regression coverage.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
homeassistant/components/rainbird/__init__.py	Registers the controller before platforms load.
homeassistant/components/rainbird/switch.py	Links zones using the controller device ID.
tests/components/rainbird/test_switch.py	Verifies zone-to-controller linkage.
tests/components/rainbird/test_init.py	Updates migration device-count expectations.

[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated no new comments.