feat: modernize cross-env with TypeScript, Vitest, and ESM-only build

BREAKING CHANGE: This is a major rewrite that changes the module format from CommonJS to ESM-only. The package now requires Node.js >=20 and only exports ESM modules (not relevant in most cases).

BREAKING CHANGE: The package.json exports have been updated to remove CommonJS support. Only ESM imports are now supported.

BREAKING CHANGE: All source files have been converted from JavaScript to TypeScript, requiring TypeScript-aware tooling for development.

- Replace Jest with Vitest for testing
- Convert all source files from .js to .ts with proper TypeScript types
- Use zshy for ESM-only builds (removes CJS support)
- Adopt @epic-web/config for TypeScript, ESLint, and Prettier
- Update to Node.js >=20 requirement
- Remove kcd-scripts dependency
- Add comprehensive e2e tests with GitHub Actions matrix testing
- Update GitHub workflow with caching and cross-platform testing
- Modernize documentation and remove outdated sections
- Update all dependencies to latest versions
- Add proper TypeScript declarations and exports

The tool maintains its original functionality while being completely modernized with the latest tooling and best practices.

Author: kentcdodds

.all-contributorsrc

@@ -18,6 +18,7 @@ learn how: http://kcd.im/pull-request
 Relevant code or config
 
 ```javascript
+
 ```
 
 What you did:

.github/ISSUE_TEMPLATE.md

@@ -0,0 +1,106 @@
+name: Auto Format
+
+on:
+  push:
+    branches: [main, develop]
+  pull_request:
+    branches: [main, develop]
+  workflow_dispatch:
+
+jobs:
+  format:
+    name: 🔧 Auto Format
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+      pull-requests: write
+    steps:
+      - name: 📥 Checkout code
+        uses: actions/checkout@v4
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+          ref: ${{ github.head_ref || github.ref_name }}
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: 24
+          cache: 'npm'
+
+      - name: Cache node_modules
+        uses: actions/cache@v4
+        with:
+          path: node_modules
+          key: ${{ runner.os }}-node-${{ hashFiles('**/package-lock.json') }}
+          restore-keys: |
+            ${{ runner.os }}-node-
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Check current formatting
+        id: format-check
+        run: |
+          if npm run format:check; then
+            echo "format_needed=false" >> $GITHUB_OUTPUT
+            echo "✅ Code is already properly formatted"
+          else
+            echo "format_needed=true" >> $GITHUB_OUTPUT
+            echo "⚠️ Code formatting issues found"
+          fi
+
+      - name: Format code
+        if: steps.format-check.outputs.format_needed == 'true'
+        run: npm run format
+
+      - name: Check for changes
+        id: changes
+        if: steps.format-check.outputs.format_needed == 'true'
+        run: |
+          if git diff --quiet; then
+            echo "has_changes=false" >> $GITHUB_OUTPUT
+            echo "ℹ️ No formatting changes to commit"
+          else
+            echo "has_changes=true" >> $GITHUB_OUTPUT
+            echo "📝 Formatting changes detected"
+          fi
+
+      - name: Configure Git
+        if: steps.changes.outputs.has_changes == 'true'
+        run: |
+          git config --local user.email "action@github.com"
+          git config --local user.name "GitHub Action"
+
+      - name: Commit and push changes
+        if: steps.changes.outputs.has_changes == 'true'
+        run: |
+          git add -A
+          git commit -m "🔧 Auto-format code with Prettier [skip ci]
+
+          This commit was automatically generated by the auto-format workflow.
+          Changes include:
+          - Code formatting fixes
+          - Consistent indentation
+          - Proper line endings"
+          git push origin HEAD:${{ github.head_ref || github.ref_name }}
+
+      - name: Comment on PR
+        if:
+          steps.changes.outputs.has_changes == 'true' && github.event_name ==
+          'pull_request'
+        uses: actions/github-script@v7
+        with:
+          script: |
+            github.rest.issues.createComment({
+              issue_number: context.issue.number,
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              body: '🔧 **Auto-formatting applied!**\n\nI\'ve automatically formatted the code using Prettier and pushed the changes. The formatting is now consistent with the project standards.'
+            })
+
+      - name: Success message
+        if:
+          steps.changes.outputs.has_changes == 'false' ||
+          steps.format-check.outputs.format_needed == 'false'
+        run: |
+          echo "✅ No formatting changes needed - code is already properly formatted!"