fix(ci): install the project before running the lint tests

tests/lint/test_tooling_configuration.py imports yaml, but the lint test
job only set up Python and ran unittest, so every push since the test
arrived failed with "ModuleNotFoundError: No module named 'yaml'". The
job gates the end-to-end tests and the image publish, which is why no
image exists for 2.1.0 or 2.1.1.

The job now installs the project exactly like the unit, integration and
security jobs, and make test-lint depends on install like its siblings.
Reproduced in a clean virtualenv: the lint suite fails on the missing
module without the install and passes all 18 tests with it.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

.github/workflows/tests.yml

@@ -21,6 +21,11 @@ jobs:
         with:
           python-version: "3.12"
 
+      - name: Install lint test dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install --ignore-installed .
+
       - name: Run lint test suite
         run: python -m unittest discover -s tests/lint -t .
 

Makefile

@@ -185,7 +185,7 @@ lint-shell:
 	docker run --rm -v "$$PWD:/mnt" -w /mnt koalaman/shellcheck:stable scripts/*.sh
 
 .PHONY: test-lint
-test-lint:
+test-lint: install
 	# Run lint guardrail tests.
 	$(PYTHON) -m unittest discover -s tests/lint -t .