ci: add AI Changelog workflow

[sjinks]

This pull request introduces a new GitHub Actions workflow to automatically generate changelog entries for pull requests using an AI-powered tool. The workflow is triggered by a specific comment (/changelog) on a pull request and ensures that only authorized users can execute it.

New GitHub Actions Workflow:

• .github/workflows/ai-changelog.yml: Added a workflow named "Generate Changelog for PR" that listens for issue_comment events. It verifies the presence of the OpenAI API key, checks if the user has write access, generates a changelog entry using the AI tool, and posts or updates a comment with the generated entry.

[Copilot]

Pull Request Overview

This PR adds a new GitHub Actions workflow that generates and posts changelog entries for pull requests when an authorized user comments /changelog.

• Introduces .github/workflows/ai-changelog.yml to listen for /changelog comments on PRs
• Verifies the OpenAI API key and user’s write access before generating an AI-powered changelog entry
• Finds or updates an existing AI-generated comment with the new entry

Comments suppressed due to low confidence (3)

.github/workflows/ai-changelog.yml:42

• The script calls core.setFailed and core.setOutput but never imports core. Add const core = require('@actions/core'); at the top of the script block.

              core.setFailed(`User ${context.payload.comment.user.login} does not have write access.`);

.github/workflows/ai-changelog.yml:17

• The workflow needs permission to post issue comments. Add issues: write under permissions so that the create-or-update-comment step can succeed.

      pull-requests: write

.github/workflows/ai-changelog.yml:58

• [nitpick] The step id fc is not descriptive. Consider renaming it to something like find_comment for clarity.

        id: fc