Add target_humidity_step attribute to humidifier

[LG-ThinQ-Integration]

Proposed change

Add attribute "target_humidity_step" to humidifier for customize step in frontend. It was discussed that this attribute is necessary to apply LG-based humidifiers. https://github.com/home-assistant/core/pull/152593#discussion_r2523708072

• core: Add attr_target_humidity_step to humidifier entity.
• frontend: Additionally, attribute is required to the step function of the humidifier control.

private get _step() { return this.stateObj.attributes.target_humidity_step ?? 1; }

Type of change

• [ ] Dependency upgrade
• [ ] Bugfix (non-breaking change which fixes an issue)
• [ ] New integration (thank you!)
• [X] 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: https://github.com/home-assistant/core/pull/152593
• Link to documentation pull request:
• Link to developer documentation pull request: https://github.com/home-assistant/developers.home-assistant/pull/2865
• Link to frontend pull request: https://github.com/home-assistant/frontend/pull/28005

Checklist

• [X] I understand the code I am submitting and can explain how it works.
• [X] The code change is tested and works locally.
• [X] Local tests pass. Your PR cannot be merged unless tests pass
• [X] There is no commented out code in this PR.
• [X] I have followed the development checklist
• [X] I have followed the perfect PR recommendations
• [X] The code has been formatted using Ruff (ruff format homeassistant tests)
• [X] Tests have been added to verify that the new code works.
• [X] 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

If the code communicates with devices, web services, or third-party tools:

• [X] The manifest file has all fields filled out correctly.
  Updated and included derived files by running: python3 -m script.hassfest.
• [ ] New or updated dependencies have been added to requirements_all.txt.
  Updated by running python3 -m script.gen_requirements_all.
• [ ] For the updated dependencies - a link to the changelog, or at minimum a diff between library versions is added to the PR description.

To help with the load of incoming pull requests:

• [ ] I have reviewed two other open pull requests in this repository.

[home-assistant[bot]]

Hey there @home-assistant/core, mind taking a look at this pull request as it has been labeled with an integration (demo) you are listed as a code owner for? Thanks!

Code owner commands

Code owners of demo can trigger bot actions by commenting:

• @home-assistant close Closes the pull request.
• @home-assistant rename Awesome new title Renames the pull request.
• @home-assistant reopen Reopen the pull request.
• @home-assistant unassign demo Removes the current integration label and assignees on the pull request, add the integration domain after the command.
• @home-assistant add-label needs-more-information Add a label (needs-more-information, problem in dependency, problem in custom component) to the pull request.
• @home-assistant remove-label needs-more-information Remove a label (needs-more-information, problem in dependency, problem in custom component) on the pull request.

[home-assistant[bot]]

Hey there @home-assistant/core, @shulyaka, mind taking a look at this pull request as it has been labeled with an integration (humidifier) you are listed as a code owner for? Thanks!

Code owner commands

Code owners of humidifier can trigger bot actions by commenting:

• @home-assistant close Closes the pull request.
• @home-assistant rename Awesome new title Renames the pull request.
• @home-assistant reopen Reopen the pull request.
• @home-assistant unassign humidifier Removes the current integration label and assignees on the pull request, add the integration domain after the command.
• @home-assistant add-label needs-more-information Add a label (needs-more-information, problem in dependency, problem in custom component) to the pull request.
• @home-assistant remove-label needs-more-information Remove a label (needs-more-information, problem in dependency, problem in custom component) on the pull request.

[home-assistant[bot]]

Please take a look at the requested changes, and use the Ready for review button when you are done, thanks :+1:

Learn more about our pull request process.

[LG-ThinQ-Integration]

@frenck Discussion: https://github.com/home-assistant/architecture/discussions/1309

[LG-ThinQ-Integration]

@frenck The discussion appears to be complete. Can we proceed with the PR?

[CoMPaTech]

@abmantis would you like this PR extended to include climate? I'd suggest we keep the PR small but just add another for climate.