chore: make plugin publish-safe for PyPI

Remove private git.eskimo.dev URLs (README install -> `pip install
certbot-dns-yeil`; setup.py url -> docs.yeil.app/dns). Update README to the
api.yeil.app/v1/dns gateway + gateway-relative paths. Flesh out setup.py
metadata (long_description from README, classifiers, python_requires,
project_urls, keywords). Add an MIT LICENSE file and a Python .gitignore
(so build/ dist/ *.egg-info/ __pycache__ stay out of the repo).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

setup.py

@@ -1,12 +1,25 @@
+import pathlib
+
 from setuptools import setup, find_packages
 
+LONG_DESCRIPTION = pathlib.Path(__file__).with_name("README.md").read_text(
+    encoding="utf-8"
+)
+
 setup(
     name="certbot-dns-yeil",
     version="3.1.0",
     description="yeil DNS Authenticator plugin for Certbot",
-    url="https://git.eskimo.dev/Yeil/certbot-dns-yeil",
+    long_description=LONG_DESCRIPTION,
+    long_description_content_type="text/markdown",
+    url="https://docs.yeil.app/dns",
+    project_urls={
+        "Documentation": "https://docs.yeil.app/dns",
+    },
     author="yeil",
     license="MIT",
+    keywords="certbot dns yeil acme letsencrypt dns-01 dns-authenticator",
+    python_requires=">=3.8",
     packages=find_packages(),
     install_requires=[
         "certbot>=1.1.0",
@@ -17,4 +30,16 @@ setup(
             "dns-yeil = certbot_dns_yeil.dns_yeil:Authenticator",
         ],
     },
+    classifiers=[
+        "Development Status :: 5 - Production/Stable",
+        "Environment :: Plugins",
+        "Intended Audience :: System Administrators",
+        "License :: OSI Approved :: MIT License",
+        "Operating System :: OS Independent",
+        "Programming Language :: Python :: 3",
+        "Programming Language :: Python :: 3 :: Only",
+        "Topic :: Internet :: Name Service (DNS)",
+        "Topic :: Security",
+        "Topic :: System :: Systems Administration",
+    ],
 )