refactor: extract common filter logic into shared runtime

Makefile

@@ -0,0 +1,23 @@
+.PHONY: build test lint demo demo-build demo-run clean
+
+build:
+	go build -o snitch .
+
+test:
+	go test ./...
+
+lint:
+	golangci-lint run
+
+demo: demo-build demo-run
+
+demo-build:
+	docker build -f demo/Dockerfile -t snitch-demo .
+
+demo-run:
+	docker run --rm -v $(PWD)/demo:/output snitch-demo
+
+clean:
+	rm -f snitch
+	rm -f demo/demo.gif
+