Update dependencies, enhance AI integration, and improve email content

- Added @google/genai dependency for enhanced AI capabilities.
- Updated CI workflow to include new environment variables for AI integration.
- Refactored AI client to support multiple providers and improved key management.
- Enhanced email templates for better user engagement and clarity.
- Updated error handling in AI-related functions to provide clearer feedback.
- Made various improvements to the application structure and code clarity.

.gitea/workflows/ci.yaml

@@ -26,7 +26,9 @@ jobs:
           IYZICO_API_KEY=${{ secrets.IYZICO_API_KEY }}
           IYZICO_SECRET_KEY=${{ secrets.IYZICO_SECRET_KEY }}
           IYZICO_BASE_URL=${{ secrets.IYZICO_BASE_URL }}
+          AI_SAGLAYICI=${{ secrets.AI_SAGLAYICI }}
           ANTHROPIC_API_KEY=${{ secrets.ANTHROPIC_API_KEY }}
+          GEMINI_API_KEY=${{ secrets.GEMINI_API_KEY }}
           EOF
 
       - name: Build & deploy