ci: update project tooling to Python 3.14

[bdamokos]

Summary

• update project and CI Python target from 3.13 to 3.14
• update mypy/Black Python targets to match Home Assistant 2026.5.x requirements
• require pytest-homeassistant-custom-component>=0.13.333, which tracks Home Assistant 2026.5.4
• mock Tuya local discovery in the config-flow success test to avoid real socket attempts under the newer test plugin

Validation

• task lint
• task type-check
• task test (557 passed)