Add devcontainer support for development

.devcontainer/Dockerfile

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+# Which Ruby version to use. You may need to use a more restrictive version,
+# e.g. `3.0`
+ARG VARIANT=3.3
+
+# Pull Microsoft's ruby devcontainer base image
+FROM mcr.microsoft.com/devcontainers/ruby:${VARIANT}
+
+# Install libsodium dependency for voice channel interactions
+RUN apt update -yq && apt install -y libsodium-dev
+
+# Ensure we're running the latest bundler, as what ships with the Ruby image may
+# not be current, and bundler will auto-downgrade to match the Gemfile.lock
+RUN gem install bundler

.devcontainer/devcontainer.json

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+{
+  "name": "Ruby",
+  "build": {
+    "dockerfile": "Dockerfile"
+  },
+
+  // Configure tool-specific properties.
+  "customizations": {
+    // Configure properties specific to VS Code.
+    "vscode": {
+      // Add the IDs of extensions you want installed when the container is created.
+      "extensions": [
+        "shopify.ruby-lsp"
+      ]
+    }
+  },
+
+  // Set the environment variables
+  // "runArgs": ["--env-file",".env"],
+
+  // Use 'forwardPorts' to make a list of ports inside the container available locally.
+  //   "forwardPorts": [],
+
+  // Use 'postCreateCommand' to run commands after the container is created.
+  "postCreateCommand": "bash .devcontainer/postcreate.sh",
+
+  // Set `remoteUser` to `root` to connect as root instead. More info: https://aka.ms/vscode-remote/containers/non-root.
+  "remoteUser": "vscode"
+}

.devcontainer/postcreate.sh

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+#!/bin/bash
+
+bundle config set path vendor/bundle
+bundle install --jobs=1