ci: add stable build, add tests.

.github/ci/build.sh

@@ -0,0 +1,18 @@
+#!/bin/bash
+## on push branch~=gh-readonly-queue/main/.*
+## on pull_request
+
+set -euo pipefail
+
+export RUSTUP_HOME=/ci/cache/rustup
+export CARGO_HOME=/ci/cache/cargo
+export CARGO_TARGET_DIR=/ci/cache/target
+if [ -f /ci/secrets/teleprobe-token.txt ]; then 
+    echo Got teleprobe token!
+    export TELEPROBE_TOKEN=$(cat /ci/secrets/teleprobe-token.txt)
+fi
+
+hashtime restore /ci/cache/filetime.json || true
+hashtime save /ci/cache/filetime.json
+
+./ci.sh