Set up todo frontend resources when first platform is set up

[emontnemery]

Proposed change

Set up todo frontend resources when first todo platform is set up to prevent loading the todo panel when there are no todo platforms

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:
• 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.
• I have followed the development checklist
• I have followed the perfect PR recommendations
• 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

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

• 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 diff between library versions and ideally a link to the changelog/release notes 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]

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

Code owner commands

Code owners of todo 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 todo 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, problem in config, problem in device, feature-request) to the pull request.
• @home-assistant remove-label needs-more-information Remove a label (needs-more-information, problem in dependency, problem in custom component, problem in config, problem in device, feature-request) on the pull request.

[Copilot]

Pull request overview

This PR delays registering the Todo built-in frontend panel and Todo WebSocket commands until a Todo platform/config entry is actually set up, so the Todo panel is not exposed when there are no Todo platforms.

Changes:

• Move Todo frontend panel + WebSocket command registration out of async_setup and into a new TodoEntityComponent that registers them on first platform/config-entry setup.
• Add tests asserting frontend/WebSocket resources are only registered after the first platform/config entry is set up.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
homeassistant/components/todo/__init__.py	Introduces TodoEntityComponent to lazily register the Todo panel/WebSocket commands after first platform/entry setup.
tests/components/todo/test_init.py	Adds coverage for when the Todo panel/WebSocket commands become registered.