chore: repo scaffold, Apache-2.0, test harness, CI workflows

Local pytest execution is skipped by owner decision: no release of
pytest-homeassistant-custom-component that pins a Home Assistant
2026.9.x floor installs on Python 3.13 (0.13.317+ requires Python
3.14, which this workstation does not have). requirements_test.txt
is pinned to the correct >=0.13.317 range for CI (Python 3.14) and
files are validated with py_compile instead of a local pytest run.

CI workflows (test.yaml, validate.yaml) moved forward from a later
task since, with local testing gone, CI is the only gate and must
exist before the code it gates.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01739Seac5eMAfNwFeiwV5r4

pyproject.toml

@@ -0,0 +1,7 @@
+[tool.pytest.ini_options]
+asyncio_mode = "auto"
+testpaths = ["tests"]
+
+[tool.ruff]
+target-version = "py313"
+line-length = 88