Add Discord notification workflow for merged pull requests

[sven-n]

Summary

This PR adds a GitHub Actions workflow that automatically sends a notification to Discord whenever a pull request is merged into the repository.

Key Changes

• Added .github/workflows/discord-merge-notification.yml workflow that:
  • Triggers on pull request merge events using pull_request_target (safe for fork PRs)
  • Constructs a formatted Discord embed message containing PR metadata
  • Posts the notification to a Discord webhook URL via curl
  • Gracefully handles missing webhook configuration with a warning

Implementation Details

• Uses pull_request_target event type to safely access secrets even for PRs from forks, without checking out or executing PR code
• Extracts PR information (number, title, author, merge details, target branch) from GitHub event context
• Builds a JSON payload using jq with:
  • PR title (truncated to 256 characters) as the embed title
  • Author information with avatar
  • Description showing merge details (merged by, target branch, repository)
  • Timestamp of the merge
  • Color code (8540383) for visual consistency
• Includes error handling to skip notification if the DISCORD_MERGE_WEBHOOK_URL secret is not configured
• Uses curl with --fail-with-body flag to ensure workflow fails if the webhook request fails

https://claude.ai/code/session_012V7N9f7ciSumzzALxciq51