chore: initial commit

.devcontainer/Dockerfile

@@ -0,0 +1,2 @@
+ARG VARIANT="16"
+FROM mcr.microsoft.com/vscode/devcontainers/javascript-node:0-${VARIANT}

.devcontainer/devcontainer.json

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+{
+  "name": "html-w3c-validator",
+  "dockerComposeFile": "./docker-compose.yml",
+  "service": "workspace",
+  "workspaceFolder": "/workspace",
+  "extensions": [
+    "editorconfig.editorconfig",
+    "esbenp.prettier-vscode",
+    "dbaeumer.vscode-eslint",
+    "davidanson.vscode-markdownlint",
+    "ms-azuretools.vscode-docker"
+  ],
+  "postAttachCommand": ["npm", "install"],
+  "remoteUser": "node"
+}

.devcontainer/docker-compose.yml

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+version: '3.0'
+
+services:
+  workspace:
+    build:
+      context: './'
+      dockerfile: './Dockerfile'
+    volumes:
+      - '..:/workspace:cached'
+    command: 'sleep infinity'