ci: Begin CI Pipeline

For now, we're only building aarch64 binaries.  The screens I intend to
deploy this on are both Raspberry Pis, and I don't yet have a way to
produce multi-arch container images to provide the build environment.

ci/build.sh

@@ -0,0 +1,5 @@
+#!/bin/sh
+
+cargo build --release
+
+ln -sr target/release $(uname -m)