ci: adopt aiopowerwall's lint/test/build job shape, add Ruff

[Bre77]

Intent

• Adopt aiopowerwall's CI job shape (lint / test / build) so this repo's gate covers what its sibling project's does.
  • Split the old typecheck job into lint (Ruff + mypy), matching aiopowerwall's step order and naming.
  • Ruff, like mypy, isn't a declared dev dependency - CI installs it ephemerally via uv run --with ruff ruff check ....
  • [tool.ruff] selects E, F, W, I, B, UP, ASYNC, SIM, RUF; RUF006 is ignored since the stream's background listen/refresh tasks are intentionally untracked fire-and-forget asyncio.create_task calls, not an oversight.
  • Fixed the resulting lint findings (import sort order, __all__ sort, collections.abc.Callable, an unnecessary quoted forward ref, a nested if) - no behavior change.
• test job now fails outright if tests/test_*.py matches nothing, instead of silently continuing - a missing test suite should be a red build, not green.
• Added a build job: uv build (wheel + sdist), twine check on the artifacts, then uploads them - catches malformed metadata/README rendering before it ever reaches a release.
• Supported-Python matrix (3.9-3.13) and existing trigger/concurrency config are unchanged.