feat: docker-compose.local.yml for local build/smoke-test

env.sample

@@ -0,0 +1,15 @@
+# Copy to .env (which is gitignored) and fill in real values:
+#   cp env.sample .env && $EDITOR .env
+
+# Required: bearer token clients must send as `Authorization: Bearer <value>`.
+# Generate with: openssl rand -hex 32
+UPDATER_API_KEY=
+
+# Optional: root directory the service is allowed to manage stacks under.
+# Defaults to /tmp for local smoke testing. For real use, set to your stacks dir,
+# e.g. /home/shcizo/self-hosted
+# STACKS_ROOT=/home/shcizo/self-hosted
+
+# Optional: build info baked into the binary via -ldflags. Not required.
+# COMMIT=$(git rev-parse --short HEAD)
+# BUILD_TIME=$(date -u +%Y-%m-%dT%H:%M:%SZ)