chore: Update devcontainer.json and Dockerfile for DevChum project

.devcontainer/Dockerfile

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+FROM mcr.microsoft.com/devcontainers/javascript-node:1-22-bookworm
+
+RUN npm uninstall -g pnpm && corepack enable pnpm

.devcontainer/devcontainer.json

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+// For format details, see https://aka.ms/devcontainer.json. For config options, see the
+// README at: https://github.com/devcontainers/templates/tree/main/src/javascript-node
+{
+  "name": "DevChum",
+  "build": {
+    "dockerfile": "Dockerfile",
+    "cacheFrom": "ghcr.io/nid-kt/devchum-devcontainer"
+  },
+
+  // Features to add to the dev container. More info: https://containers.dev/features.
+  // "features": {},
+
+  // 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": "corepack prepare && pnpm i --frozen-lockfile",
+
+  // Configure tool-specific properties.
+  "customizations": {
+    "vscode": {
+      "settings": {
+        "editor.defaultFormatter": "esbenp.prettier-vscode",
+        "editor.formatOnSave": true
+      },
+      "extensions": ["dbaeumer.vscode-eslint", "esbenp.prettier-vscode"]
+    }
+  }
+
+  // Uncomment to connect as root instead. More info: https://aka.ms/dev-containers-non-root.
+  // "remoteUser": "root"
+}

.github/dependabot.yml

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+# To get started with Dependabot version updates, you'll need to specify which
+# package ecosystems to update and where the package manifests are located.
+# Please see the documentation for more information:
+# https://docs.github.com/github/administering-a-repository/configuration-options-for-dependency-updates
+# https://containers.dev/guide/dependabot
+
+version: 2
+updates:
+  - package-ecosystem: "devcontainers"
+    directory: "/"
+    schedule:
+      interval: daily
+
+  - package-ecosystem: "npm"
+    directory: "/"
+    schedule:
+      interval: "daily"
+
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "daily"

.github/workflows/ci-in-devcontainer.yml

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+name: CI in DevContainer
+
+on:
+  push:
+  pull_request:
+
+jobs:
+  ci-in-devcontainer:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Export
+        uses: devcontainers/[email protected]
+        with:
+          cacheFrom: ghcr.io/nid-kt/devchum-devcontainer
+          push: never
+          runCmd: pnpm export

.github/workflows/push-devcontainer.yml

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+name: Push DevContainer
+
+on:
+  push:
+    branches:
+      - main
+
+jobs:
+  push-devcontainer:
+    runs-on: ubuntu-latest
+    permissions:
+      packages: write
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Login to GitHub Container Registry
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.repository_owner }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Push DevContainer
+        uses: devcontainers/[email protected]
+        with:
+          imageName: ghcr.io/nid-kt/devchum-devcontainer
+          cacheFrom: ghcr.io/nid-kt/devchum-devcontainer
+          push: always

.vscode/extensions.json

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+{
+  "recommendations": ["esbenp.prettier-vscode", "dbaeumer.vscode-eslint"]
+}