Improve Tuya HVACMode handling

[epenet]

Proposed change

Related to #157876 / #158258 / #158452

• if the climate entity is missing both switch and mode wrapper, it now returns None (previously returned OFF)
• if the climate entity has a mode wrapper, but the mode wrapper returns an invalid value (not present in enum), it now returns None (previously returned default switch_only_hvac_mode)

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 #
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[home-assistant]

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

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[epenet]

5ls2jw49hpczwqng does not expose switch or mode wrapper.

[epenet]

B0eP8qYAdpUo4yR9 does not expose switch or mode wrapper.

[epenet]

d7woucobqi8ncacf does not expose switch or mode wrapper.

[Copilot]

Pull request overview

This PR improves HVAC mode handling for Tuya climate entities by returning None instead of OFF in cases where the device state is truly unknown. Previously, the integration would incorrectly return HVACMode.OFF for devices with no control mechanism (neither switch nor mode wrapper) or when the mode wrapper returned an invalid/unmapped value.

Key changes:

• Returns None when both switch and mode wrappers are missing (instead of OFF)
• Returns None when mode value doesn't map to a valid HVAC mode (instead of falling back to switch_only_hvac_mode)
• Updates return type annotation to HVACMode | None to reflect the new behavior

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
homeassistant/components/tuya/climate.py	Refactored hvac_mode property to properly return None for unknown states; updated return type to HVACMode | None; improved logic clarity by explicitly checking for None wrapper before reading status
tests/components/tuya/snapshots/test_climate.ambr	Updated test snapshots for devices with no switch/mode wrappers - correctly changed state from 'off' to 'unknown' for three climate entities