Automatically detect device class in vizio config flow

[raman325]

Proposed change

Follow-up to the review discussion on #177590, where @gjohansson-ST asked whether the reconfigure flow should also cover device class/token. Rather than exposing the device class in more flows, this PR removes the "Device type" selector from the config flow entirely and detects it automatically. A revised reconfigure flow building on this will come in a separate PR — the scope here is intentionally only the auto-classification.

• The "Device type" field is removed from the user step schema, along with its strings.json entry and the DEFAULT_DEVICE_CLASS constant.
• The device class is now detected automatically using the same probe zeroconf discovery already uses: vizaio's async_is_tv, which makes a single unauthenticated request to the SmartCast audio-settings endpoint (sound bars answer without auth, TVs reject it until paired).
• Detection is shared via a new _async_detect_device_class helper, which also passes Home Assistant's shared aiohttp session into async_is_tv (the zeroconf path previously created its own session).
• The zeroconf step passes the detected class into the user step, which only probes when the class isn't already provided.
• A wrong guess cannot create a bad entry: the serial-number fetch immediately afterwards aborts with cannot_connect if the device isn't reachable.
• Existing config entries are unaffected (device_class remains stored in entry data). Not a breaking change — the setup form simply has one fewer field.
• Tests: a new vizio_detect_tv fixture was added, and the two user-form-path tests now cover both detection outcomes (TV and speaker). All 82 vizio tests pass locally.

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: the review thread on Add reconfigure flow to vizio #177590 (Add reconfigure flow to vizio #177590)
• Link to documentation pull request: Restructure vizio documentation around config flow setup home-assistant.io#47122 (the pending vizio docs restructure PR will be updated to drop the device type field description)
• 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.

[Copilot]

Copilot was unable to review this pull request because the user who requested the review has reached their quota limit.