Adds [tool.ruff] and [tool.ty] config to pyproject.toml with a curated
ruff rule set (E, F, W, I, UP, B, C4, SIM, RUF, ASYNC, LOG, G, PIE, RET,
PERF, N), pins ruff/ty in requirements-dev.txt, reformats the whole tree
with `ruff format`, and fixes the pre-existing lint and type-check debt
those tools surfaced so both run clean.
Production-code type fixes include: HA's ConfigFlowResult vs. the
generic FlowResult in config_flow.py, narrowing BoundEntity.desc to its
platform-specific subclass (SelectDesc/NumberDesc/SensorDesc/etc.) via
cast() instead of an unchecked annotation, converting HA device_class
strings to their proper enum types, a resolve_registry callback typed
as `object` instead of `DeviceRegistry | None`, and a couple of other
narrow correctness fixes (CA key type validation, an index-out-of-bounds
false positive from an empty-tuple fallback, a bool/dict argument swap).
Test-file fixes are mechanical: narrowing SamsungEntityDescription to
the correct subclass via isinstance()/cast() before accessing
subclass-only fields, and asserting Optional write_fn/unit_fn fields
are set before calling them.
README.md and requirements-dev.txt already document that the test
harness needs Python 3.13+ (pytest-homeassistant-custom-component
doesn't resolve below it), but only in prose. Add requires-python so
pip fails fast with a clear message on an older interpreter instead of
a wall of "Requires-Python >=3.13" version-list noise.
Marc Billow