Updating devcontainer setup and related documentation

.devcontainer/Dockerfile

@@ -1,4 +1,15 @@
-FROM mcr.microsoft.com/vscode/devcontainers/javascript-node:16
-RUN apt-get update && export DEBIAN_FRONTEND=noninteractive \
-    && apt-get install ffmpeg gnupg2 -y
+# [Choice] Node.js version (use -bullseye variants on local arm64/Apple Silicon): 18, 16, 14, 18-bullseye, 16-bullseye, 14-bullseye, 18-buster, 16-buster, 14-buster
+ARG VARIANT=16
+FROM mcr.microsoft.com/devcontainers/javascript-node:0-${VARIANT} as base
+
+# Setup the node environment
 ENV NODE_ENV=development
+
+# Install additional OS packages.
+RUN apt-get update && \
+  DEBIAN_FRONTEND=noninteractive apt-get -y install --no-install-recommends \
+    curl tzdata ffmpeg && \
+  rm -rf /var/lib/apt/lists/*
+
+# Move tone executable to appropriate directory
+COPY --from=sandreas/tone:v0.1.2 /usr/local/bin/tone /usr/local/bin/