Enhance linting script and workflow

[joshjohanning]

• Both lint-gh-cli-readme and lint-scripts-readme jobs now save their lint output to result files and upload them as artifacts, making it easier to review linting issues after the workflow runs.
• A new post-results job is added to aggregate these lint results and post them as a formatted, sticky comment on the pull request, ensuring contributors get immediate feedback on README quality.
• Read-only permissions for contents are set on lint jobs, and write permissions for pull requests are set on the posting job, following best practices for GitHub Actions security.
• Numbering each linting issue
• Adding an emoji classifying each linting issue.

New example:

1. 📝 The file adding-new-file-script.sh is not mentioned in the README.md
2. 🔒 The file adding-new-file-script.sh does not have execution permissions
3. 🐛 The file adding-new-file-script.sh has a bash syntax error
        gh-cli/adding-new-file-script.sh: line 31: unexpected EOF while looking for matching ``'

❌ Found 3 issues that need to be addressed.

[github-actions]

📋 README Lint Results

⚡ gh-cli/README.md

✅ No issues found.

🔧 scripts/README.md

✅ No issues found.

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Lint results updated at Sat Aug 23 13:53:53 UTC 2025