AAP-85334: Replace Black + Flake8 with Ruff

Migrate Python linting and formatting toolchain from Black (formatter)
and Flake8 (linter) to Ruff, which provides both in a single tool.

- pyproject.toml: remove [tool.black], add [tool.ruff] config sections
- tox.ini: replace black+flake8 deps/commands with ruff in linters env
- awxkit/tox.ini: replace flake8 with ruff in lint env
- Makefile: replace `black` target with `format` + `lint`, keep `black`
  as legacy alias, update `check` and `api-lint`
- pre-commit.sh: use `ruff format --check`, honor AWX_IGNORE_RUFF
- requirements_dev.txt: swap black/flake8 for ruff
- Dockerfile.j2: install ruff instead of black
- CONTRIBUTING.md: update tool references
- Fix noqa comments to use # separator instead of ; (ruff requirement)
- Add noqa: F841 for false positive in awxkit/cli/__init__.py

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Makefile

@@ -348,9 +348,17 @@ run-ws-heartbeat:
 reports:
 	mkdir -p $@
 
-black: reports
-	@command -v black >/dev/null 2>&1 || { echo "could not find black on your PATH, you may need to \`pip install black\`, or set AWX_IGNORE_BLACK=1" && exit 1; }
-	@(set -o pipefail && $@ $(BLACK_ARGS) awx awxkit awx_collection | tee reports/$@.report)
+## awx_collection is excluded: ansible-test sanity runs its own linters which conflict with ruff
+format: reports
+	@command -v ruff >/dev/null 2>&1 || { echo "could not find ruff on your PATH, you may need to \`pip install ruff\`" && exit 1; }
+	@(set -o pipefail && ruff format $(RUFF_FORMAT_ARGS) awx awxkit | tee reports/format.report)
+
+lint: reports
+	@command -v ruff >/dev/null 2>&1 || { echo "could not find ruff on your PATH, you may need to \`pip install ruff\`" && exit 1; }
+	ruff check awx awxkit
+
+## Legacy alias
+black: format
 
 $(GIT_COMMON_DIR)/hooks/pre-commit:
 	ln -sf ../../pre-commit.sh $(GIT_COMMON_DIR)/hooks/pre-commit
@@ -369,11 +377,11 @@ genschema-yaml: awx-link reports
 	fi; \
 	$(MANAGEMENT_COMMAND) spectacular --format openapi --file schema.yaml
 
-check: black
+check: format
 
 api-lint:
-	BLACK_ARGS="--check" $(MAKE) black
-	flake8 awx
+	RUFF_FORMAT_ARGS="--check" $(MAKE) format
+	$(MAKE) lint
 	yamllint -s .
 
 ## Run egg_info_dev to generate awx.egg-info for development.