DEVX-83: fix: fail lint-dockerfiles when hadolint is missing

Makefile

@@ -33,6 +33,8 @@ setup-release: $(VENV)/bin/activate .env
 # Setup for pre-built image jobs (deps already in image, just link venv + install project)
 setup-image:
 	@if [ -d /opt/venv ]; then ln -sf /opt/venv .venv; . .venv/bin/activate && pip install -e . --no-deps 2>/dev/null; \
+		export PATH="$$HOME/.local/bin:$$PATH"; \
+		python3 -m devx.tools.install_tools --tool hadolint 2>/dev/null || true; \
 	else echo "[setup-image] /opt/venv not found — falling back to setup-ci"; $(MAKE) setup-ci; fi
 
 .env:
@@ -101,12 +103,12 @@ lint-all: lint workflow-lint lint-dockerfiles
 
 lint-dockerfiles:
 	@echo "[lint-dockerfiles] Linting Dockerfiles with hadolint..."
-	@if command -v hadolint >/dev/null 2>&1; then \
-		find docker -name 'Dockerfile*' -exec hadolint {} +; \
-		echo "[lint-dockerfiles] All Dockerfiles passed."; \
-	else \
-		echo "[lint-dockerfiles] hadolint not found — skipping (install with: pip install hadolint or download from GitHub)"; \
+	@if ! command -v hadolint >/dev/null 2>&1; then \
+		echo "[lint-dockerfiles] ERROR: hadolint not found. Install from https://github.com/hadolint/hadolint/releases" >&2; \
+		exit 1; \
 	fi
+	@find docker -name 'Dockerfile*' -exec hadolint {} +
+	@echo "[lint-dockerfiles] All Dockerfiles passed."
 
 test-unit: devx-test-unit