feat(workflows): add AI-powered contribution validator

[SpiGAndromeda]

What

Adds a GitHub Actions workflow that validates PRs against contribution guidelines using Gemini AI and provides actionable feedback.

Why

Manual review of contribution standards is inconsistent and time-consuming. This validator ensures consistent quality across all contributions while providing immediate feedback.

Live Demonstrations

See the validator in action:

• Good contribution example - passes validation
• Poor contribution example - shows improvement suggestions
• Multi-commit example - demonstrates commit consolidation advice

Key Features

• Validates all contributions using Gemini AI
• Updates existing comments with timestamps
• Security-first design with minimal permissions
• Abuse prevention via PR size limits
• Graceful degradation if API unavailable
• Cost-effective: ~1,500 tokens per PR

Configuration

1. Set GEMINI_API_KEY secret in repository settings
2. Optionally add to branch protection as required check

Technical Details

• Permissions: contents:read, pull-requests:write, statuses:write
• Triggers: PR opened, synchronized, edited
• Rate limits: 60 requests/min by Gemini API
• Abuse prevention: Skips PRs with additions > 10k, files > 100, commits > 50

[SpiGAndromeda]

You can get an API Key for the project by opening going to https://aistudio.google.com/app/apikey and create one there. The limits are more than suffienct for this purpose.

[nizos]

Hi @SpiGAndromeda,

Thank you for this thoughtful contribution!

For where TDD Guard currently stands, this feels a bit premature. Our contribution volume is still manageable with manual review, and I'd prefer to avoid the added complexity and maintenance burden of external dependencies at this stage. The CONTRIBUTING.md guidelines you've created are excellent and more than sufficient for our current needs.

I'm closing this for now, but please don't let this discourage you! If you're interested in contributing more, I'd especially welcome help with support for more languages and test frameworks.

Thanks again for taking the time to improve our workflow!

[SpiGAndromeda]

I appreciate the honest response and it's totally fine. It was fun to implement it and I will create a GH action from it.