refactor: Valve mirror module, golden menu test, local and CI checks

Makefile

@@ -0,0 +1,24 @@
+# Local checks, the same as CI's: make check
+SH := steamify.sh $(wildcard lib/*.sh) ui/steamify-app.sh .github/tools/bundle.sh
+# The unit tests live in ../steamify-cachyos-dev/tests (REPO points at this checkout).
+DEV ?= ../steamify-cachyos-dev
+TESTS := $(wildcard $(DEV)/tests/*-test.sh)
+
+.PHONY: check syntax lint test bundle fmt-check
+check: syntax lint test bundle
+
+syntax:
+	@for f in $(SH); do bash -n "$$f" || exit 1; done
+	python3 -m py_compile ui/steamify-ui patches/*.py
+
+lint:
+	@command -v shellcheck >/dev/null && shellcheck -S warning $(SH) || echo "shellcheck not installed: skipped"
+
+test:
+	@for t in $(TESTS); do echo "== $$t"; REPO="$(CURDIR)" bash "$$t" || exit 1; done
+
+bundle:
+	.github/tools/bundle.sh dist/steamify.sh
+
+fmt-check:
+	@command -v shfmt >/dev/null && shfmt -d -i 4 -ci $(SH) || echo "shfmt not installed: skipped"