Migrate linting to prek, bump Python to 3.14

[Snuffy2]

Migrate CI and local tooling from pre-commit to prek and update project tooling for Python 3.14. Changes include:

• CI: simplified .github/workflows/linters.yml to checkout and run the prek action (removed detailed setup/cache/install steps).
• Local tooling docs: AGENTS.md updated to instruct use of prek and prek run -a.
• Pre-commit config: .pre-commit-config.yaml updated with additional shellcheck dependency, added a mypy hook and extra dependencies, removed pre-commit.ci config blocks.
• pyproject.toml: requires-python set to >=3.14, lint tooling updated to use prek, mypy/ruff configuration adjusted (python_version, target-version, required-version, pydocstyle convention and property-decorators).
• Code/tests: small refactors in tests to replace inline lambdas with named helper functions for is_attr_blank/set_attr; several exception handling lines edited in helpers.py, sensor.py and tests (exception clause formatting changed).

These changes modernize the lint/test workflow and align tooling with Python 3.14 and the chosen prek-based tooling.

[github-actions]

Coverage report

Click to see where and how coverage changed

File	Statements	Missing	Coverage	Coverage (new stmts)	Lines missing
custom_components/places
helpers.py
sensor.py
Project Total

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