feat: update sync workflow to use MIRROR_DISCLAIMER.md file (#300)

- Add MIRROR_DISCLAIMER.md file to base-action directory
- Update sync workflow to concatenate disclaimer with README
- Cleaner approach than embedding content in workflow file

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-authored-by: Claude <noreply@anthropic.com>

.github/workflows/sync-base-action.yml

@@ -56,6 +56,12 @@ jobs:
           # Copy all contents from base-action
           cp -r ../base-action/. .
 
+          # Prepend mirror disclaimer to README if both files exist
+          if [ -f "README.md" ] && [ -f "MIRROR_DISCLAIMER.md" ]; then
+            cat MIRROR_DISCLAIMER.md README.md > README.tmp
+            mv README.tmp README.md
+          fi
+
           # Check if there are any changes
           if git diff --quiet && git diff --staged --quiet; then
             echo "No changes to sync"

base-action/MIRROR_DISCLAIMER.md

@@ -0,0 +1,11 @@
+# ⚠️ This is a Mirror Repository
+
+This repository is an automated mirror of the `base-action` directory from [anthropics/claude-code-action](https://github.com/anthropics/claude-code-action).
+
+**Do not submit PRs or issues to this repository.** Instead, please contribute to the main repository:
+
+- 🐛 [Report issues](https://github.com/anthropics/claude-code-action/issues)
+- 🔧 [Submit pull requests](https://github.com/anthropics/claude-code-action/pulls)
+- 📖 [View documentation](https://github.com/anthropics/claude-code-action#readme)
+
+---