chore: remove all extras from tox.ini, use dev dep group

Author: fselmo

tox.ini

@@ -13,22 +13,10 @@ runner = uv-venv-lock-runner
 [testenv]
 basepython = python3.14
 uv_python = >=3.12
-allowlist_externals =
-    pytest
-    ruff
-    mypy
-    codespell
-    mdformat
-    mkdocs
+dependency_groups = dev
 
 [testenv:all-checks]
 description = Run all quality checks (lint, typecheck, spellcheck, mdformat)
-extras =
-    lint
-    typecheck
-    test
-    docs
-    mdformat
 commands =
     {[testenv:lint]commands}
     {[testenv:typecheck]commands}
@@ -37,52 +25,41 @@ commands =
 
 [testenv:lint]
 description = Lint and code formatting checks (ruff)
-extras = lint
 commands =
     ruff check --no-fix --show-fixes src tests
     ruff format --check src tests
 
 [testenv:fix]
 description = Auto-fix linting and formatting issues (ruff)
-extras = lint
 commands =
     ruff check --fix src tests
     ruff format src tests
 
 [testenv:typecheck]
 description = Run type checking (mypy)
-extras =
-    typecheck
-    test
 commands = mypy src tests
 
 [testenv:spellcheck]
 description = Run spell checking (codespell)
-extras = docs
 commands = codespell src tests docs README.md CLAUDE.md --skip="*.lock,*.svg,.git,__pycache__,.mypy_cache,.pytest_cache" --ignore-words=.codespell-ignore-words.txt
 
 [testenv:mdformat]
 description = Check markdown formatting for docs (mdformat)
-extras = mdformat
 commands = mdformat docs/
 
 [testenv:pytest]
 description = Run tests (pytest)
-extras = test
 # parallelize with `auto` but keep max processes reasonable for CI
 commands = pytest {posargs} tests -n auto --maxprocesses=10 --durations=10 --dist=worksteal
 
 [testenv:pytest-cov]
 description = Run tests with coverage (pytest)
-extras = test
 commands = pytest --cov --cov-report=html --cov-report=term {posargs}
 
 [testenv:docs]
 description = Serve documentation locally (mkdocs)
-extras = docs
 commands = mkdocs serve {posargs}
 
 [testenv:docs-build]
 description = Build documentation (mkdocs)
-extras = docs
 commands = mkdocs build {posargs}