ci: add GitHub Actions workflows

Add workflows for:
- Build: CI builds on PRs and pushes to main
- Publish: Manual publish to VS Code Marketplace
- Lint PR Title: Validate conventional commit format
- Preview Changelog: Generate release notes preview
- Contributors: Auto-update contributors in README

Closes #9

Author: CalvinAllen

.github/workflows/build.yml

@@ -0,0 +1,22 @@
+name: Build
+
+on:
+  workflow_dispatch:
+  pull_request:
+    types: [opened, reopened, synchronize]
+    paths:
+      - 'src/**'
+      - 'webview-ui/**'
+      - 'package.json'
+      - 'package-lock.json'
+      - 'tsconfig.json'
+      - '.github/workflows/build.yml'
+  push:
+    branches:
+      - main
+
+jobs:
+  build:
+    uses: CodingWithCalvin/.github/.github/workflows/vsc-vsix-build.yml@main
+    with:
+      extension-name: VSC-VsixManifestDesigner

.github/workflows/contributors.yml

@@ -0,0 +1,13 @@
+name: Update Contributors
+
+on:
+  schedule:
+    - cron: '0 6 * * *' # 1:00 AM EST / 2:00 AM EDT
+  workflow_dispatch:
+
+jobs:
+  contributors:
+    uses: CodingWithCalvin/.github/.github/workflows/contributors.yml@main
+    with:
+      output-format: html
+    secrets: inherit

.github/workflows/lint-pr-title.yml

@@ -0,0 +1,33 @@
+name: Lint PR Title
+
+on:
+  pull_request:
+    types: [opened, edited, reopened, synchronize]
+
+permissions:
+  contents: read
+  pull-requests: read
+
+jobs:
+  lint-pr-title:
+    name: Lint PR Title
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+
+      - name: Install commitlint
+        run: |
+          npm install --save-dev @commitlint/cli@18.4.3 @commitlint/config-conventional@18.4.3
+
+      - name: Validate PR title
+        env:
+          PR_TITLE: ${{ github.event.pull_request.title }}
+        run: |
+          echo "Validating PR title: $PR_TITLE"
+          echo "$PR_TITLE" | npx commitlint --verbose

.github/workflows/preview-changelog.yml

@@ -0,0 +1,12 @@
+name: Preview Changelog
+
+run-name: Preview release notes for next release
+
+on:
+  workflow_dispatch:
+
+jobs:
+  preview:
+    name: Preview
+    uses: CodingWithCalvin/.github/.github/workflows/generate-changelog.yml@main
+    secrets: inherit

.github/workflows/publish.yml

@@ -0,0 +1,15 @@
+name: Publish to VS Code Marketplace
+
+on:
+  workflow_dispatch:
+
+jobs:
+  publish:
+    uses: CodingWithCalvin/.github/.github/workflows/vsc-vsix-publish.yml@main
+    with:
+      extension-name: VSC-VsixManifestDesigner
+      display-name: "VSIX Manifest Designer"
+      marketplace-id: CodingWithCalvin.vsix-manifest-designer
+      description: "A visual designer for VS Code extension manifest files"
+      hashtags: "#vscode #extension #manifest #designer"
+    secrets: inherit