feat: add APort GitHub PR verification app

[jamilahmadzai]

Closes #28

Summary

• Adds a Probot-based GitHub App example for APort PR verification.
• Verifies pull request events against a configurable APort policy pack.
• Resolves agent ids from PR author, static config, author map, or branch name.
• Publishes GitHub check-run results with success, failure, or neutral conclusions.
• Includes repository configuration example, setup documentation, environment sample, and unit tests.
• Adds the GitHub PR Verification App to the root README integration table.

Testing

cd examples/developer-tools/github-app
npm test
npm run check
npm view probot@^13.4.0 version
git diff --check

Result:

10 Node tests passed.
Syntax checks passed.
probot ^13.4.0 resolves on npm.

Payout

Payment method: PayPal jamilurrehman722@gmail.com.