build(make): add lint target and run it as part of make test

`make lint` runs ruff on src and tests directly on the host, using the
same invocation as the lint-python workflow so local and CI agree. The
script fails with a clear install hint when ruff is not on PATH.

`make test` now depends on `lint`, so linting runs before the container
images are built.

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

Makefile

@@ -2,6 +2,7 @@
         build build-no-cache build-no-cache-all build-missing \
 		delete-volumes purge \
         test test-unit test-e2e test-integration test-env-virtual test-env-nix \
+        lint \
 		setup setup-venv setup-nix
 
 # Distro
@@ -82,6 +83,13 @@ build-no-cache-all:
 	  PKGMGR_DISTRO="$$d" $(MAKE) build-no-cache; \
 	done
 
+# ------------------------------------------------------------
+# Lint targets (run on the host, not in a container)
+# ------------------------------------------------------------
+
+lint:
+	@bash scripts/lint/python.sh
+
 # ------------------------------------------------------------
 # Test targets (delegated to scripts/test)
 # ------------------------------------------------------------
@@ -101,8 +109,8 @@ test-env-virtual: build-missing
 test-env-nix: build-missing
 	@bash scripts/test/test-env-nix.sh
 
-# Combined test target for local + CI (unit + integration + e2e)
-test: test-env-virtual test-unit test-integration test-e2e
+# Combined test target for local + CI (lint + unit + integration + e2e)
+test: lint test-env-virtual test-unit test-integration test-e2e
 
 delete-volumes: 
 	@docker volume rm "pkgmgr_nix_store_${PKGMGR_DISTRO}" "pkgmgr_nix_cache_${PKGMGR_DISTRO}" || echo "No volumes to delete."

scripts/lint/python.sh

@@ -0,0 +1,15 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+echo "============================================================"
+echo ">>> Running RUFF lint on src and tests (local, no container)"
+echo "============================================================"
+
+if ! command -v ruff >/dev/null 2>&1; then
+  echo "ruff is not installed or not on PATH." >&2
+  echo "Install it with: pip install ruff" >&2
+  exit 127
+fi
+
+ruff --version
+ruff check src tests