chore: adopt the NAPALM driver standard

- CI moves to .gitea/workflows/ci.yml and calls the shared driver workflow
  of NAPALM/driver-standard; .github/ is gone.
- license = "Apache-2.0" and a LICENSE file: the package declared no
  license at all. README and CHANGELOG.md, py.typed, links to
  git.netork.io, a dev extra with floors; .venv/ and build output ignored.
- Floors on every dependency: napalm-device-types>=4.21.1 (had none),
  napalm>=4.0 (what napalm-device-types needs) and requests>=2.28.0.
  Without them the lowest CI job resolves napalm 0.10, which does not
  build; the tests pass at exactly these floors.
- mypy strict for the package; napalm_yealink.yealink is exempt for now
  (20 errors), recorded in the quality baseline with get_facts'
  complexity. Coverage floor 42 % (measured 42.61 %).

Closes #4

CHANGELOG.md

@@ -0,0 +1,17 @@
+# Changelog
+
+All notable changes to this driver. The format follows
+[Keep a Changelog](https://keepachangelog.com/), versions follow
+[Semantic Versioning](https://semver.org/).
+
+## [Unreleased]
+
+### Changed
+- The driver follows the NAPALM driver standard
+  (https://git.netork.io/NAPALM/driver-standard): CI on Gitea runs ruff, mypy, the
+  tests on Python 3.10–3.13 and at the lowest declared versions, bandit, pip-audit and
+  a build check, and a release tag publishes to PyPI. The package is now licensed under
+  Apache-2.0 and ships a LICENSE file, a README and `py.typed`. It needs
+  napalm-device-types 4.21.1 or later.
+- A failed logout and an unreadable system info in `get_facts()` are now logged at
+  debug level.