fix(models): accept integer ErrorCode/WarningCode in ApplianceStatus

[Mista-P]

Summary

GetApplianceOverview returns ErrorCode and WarningCode as integers (0 when the appliance is healthy), but ApplianceStatus types them as str. In pydantic v2 that fails strict string validation, so get_appliance_overview() raises for any hub whose appliances report a numeric code:

2 validation errors for ApplianceStatus
ErrorCode
  Input should be a valid string [type=string_type, input_value=0, input_type=int]
WarningCode
  Input should be a valid string [type=string_type, input_value=0, input_type=int]

In the Home Assistant integration this surfaces as "Failed setup, will retry: Unexpected error fetching status", and the integration never finishes loading.

This adds a mode="before" validator that turns int into str for those two fields (and leaves bool alone), so the public type stays str | None and existing callers are unaffected.

Testing

• New test_appliance_status_accepts_integer_error_and_warning_codes (fails on main, passes here).
• ruff check, ruff format --check, mypy and pytest pass locally. The one exception is test_repo_scripts.py::test_check_md_alerts_passes, which also fails on main under macOS's bash 3.2 (mapfile: command not found).
• Against a live hub: the same coercion, applied from the Home Assistant integration, fixed setup, and a powered appliance reports status.

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