Initial project structure for Wrenn Sandbox

Set up directory layout, Makefiles, go.mod files, docker-compose,
and empty placeholder files for all packages.

envd/Makefile

@@ -0,0 +1,17 @@
+LDFLAGS := -s -w
+
+.PHONY: build clean fmt vet
+
+build:
+	CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -ldflags="$(LDFLAGS)" -o envd .
+	@file envd | grep -q "statically linked" || \
+		(echo "ERROR: envd is not statically linked!" && exit 1)
+
+clean:
+	rm -f envd
+
+fmt:
+	gofmt -w .
+
+vet:
+	go vet ./...