Support KNX fan entity configuration from UI

[farmio]

Proposed change

Support KNX fan entity configuration from UI

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:
• Link to documentation pull request:
• Link to developer documentation pull request: Support KNX fan entity configuration from UI home-assistant.io#42594
• Link to frontend pull request:

Checklist

• I understand the code I am submitting and can explain how it works.
• The code change is tested and works locally.
• Local tests pass. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
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• The code has been formatted using Ruff (ruff format homeassistant tests)
• Tests have been added to verify that the new code works.
• Any generated code has been carefully reviewed for correctness and compliance with project standards.

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated for www.home-assistant.io

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[home-assistant]

Hey there @Julius2342, @marvin-w, mind taking a look at this pull request as it has been labeled with an integration (knx) you are listed as a code owner for? Thanks!

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[Copilot]

Pull request overview

This PR adds UI configuration support for KNX fan entities, enabling users to configure fans through the Home Assistant UI instead of requiring YAML configuration. The implementation follows established patterns from other KNX platform entities like light, switch, and cover.

Key changes:

• Refactored the fan platform to support both YAML and UI configuration
• Added storage schema and UI strings for fan entity configuration
• Introduced support for two fan speed modes: percentage-based and step-based control

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
homeassistant/components/knx/const.py	Added FanConf class for common fan config keys and included Platform.FAN in SUPPORTED_PLATFORMS_UI
homeassistant/components/knx/schema.py	Updated YAML schema to use FanConf.MAX_STEP instead of local constant for consistency
homeassistant/components/knx/fan.py	Refactored to support both UI and YAML configuration by splitting into KnxYamlFan and KnxUiFan classes with a common _KnxFan base class
homeassistant/components/knx/storage/const.py	Moved CONF_GA_STEP to common section (used by both cover and fan) and added fan-specific constants (CONF_SPEED, CONF_GA_SPEED, CONF_GA_OSCILLATION)
homeassistant/components/knx/storage/entity_store_schema.py	Added FAN_KNX_SCHEMA with GroupSelect for percentage vs step mode configuration
homeassistant/components/knx/strings.json	Added comprehensive user-facing strings for fan configuration UI with descriptions for all options
tests/components/knx/test_fan.py	Updated existing tests to use FanConf.MAX_STEP and added new parametrized tests for UI creation and storage loading
tests/components/knx/fixtures/config_store_fan.json	Added test fixture with two fan configurations (step mode with oscillation and percentage mode)