Update package metadata and dev experience

hatch.toml

@@ -0,0 +1,38 @@
+[envs.default]
+features = ["dev"]
+dependencies = [
+    "jinja2 < 3.1.0",
+    "pytest >= 7.1.3, <8",
+    "pytest-aiohttp >= 1.0.4, <2",
+    "pytest-cov >= 2.12.1, <3",
+    "syrupy >= 3.0.0, <4",
+    "time-machine >= 2.6.0, <3",
+]
+[envs.default.scripts]
+test = "pytest --cov-report term-missing --cov=textual tests/ -vv"
+test-snapshot-update = "pytest --cov-report term-missing --cov=textual tests/ -vv --snapshot-update"
+unit-test = 'pytest --cov-report term-missing --cov=textual tests/ -vv -m "not integration_test"'
+
+[envs.lint]
+detached = true
+dependencies = [
+    "black >= 22.3.0, <23",
+    "mypy >= 0.982, <1",
+    "pre-commit >= 2.12.1, <3",
+]
+[envs.lint.scripts]
+format = "black src"
+check = "black --check src"
+typing = "mypy src/textual"
+
+[envs.docs]
+dependencies = [
+    "mkdocs >= 1.3.0, <2",
+    "mkdocs-material >= 8.2.15, <9",
+    "mkdocstrings[python] >= 0.19.0, <1",
+]
+[envs.docs.scripts]
+build = "mkdocs build"
+deploy = "mkdocs gh-deploy"
+serve = "mkdocs serve"
+help = "mkdocs --help"