seamless sandboxing (just set GEMINI_CODE_SANDBOX=true in .env) (#76)

scripts/build.sh

@@ -0,0 +1,16 @@
+#!/bin/bash
+set -euo pipefail
+
+# npm install if node_modules was removed (e.g. via npm run clean or scripts/clean.sh)
+if [ ! -d "node_modules" ]; then
+    npm install
+fi
+
+# build all workspaces/packages
+npm run build --workspaces
+
+# also build container image if GEMINI_CODE_SANDBOX is set (can be in .env file)
+# skip (-s) npm install + build since we did that above
+if [[ "${GEMINI_CODE_SANDBOX:-}" =~ ^(1|true)$ ]] || grep -qiE '^GEMINI_CODE_SANDBOX *= *(1|true)' .env; then
+    scripts/build_sandbox.sh -s
+fi