Mac mini support: arm64 cross-build installed beside the binary and pushed by arch; ARM machine name from the device tree

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

Makefile

@@ -23,7 +23,11 @@ go:
 dev:
 	cd web && npm run dev
 
-deploy: build
+# arm64 sibling for aarch64 machines (Mac mini); the hub pushes it to them
+cross:
+	CGO_ENABLED=0 GOOS=linux GOARCH=arm64 $(GO) build -trimpath -ldflags "-s -w -X main.version=$(VERSION)" -o bin/hamlab-linux-arm64 ./cmd/hamlab
+
+deploy: build cross
 	./deploy/install.sh
 	@sleep 1; $(PREFIX)/hamlab push-nodes || true