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.

package.json

@@ -15,6 +15,7 @@
   "dependencies": {
     "@anthropic-ai/sdk": "^0.112.4",
     "@cds/city": "^1.1.0",
+    "@google/genai": "^2.15.0",
     "@libsql/client": "^0.17.4",
     "@number-flow/react": "^0.6.2",
     "@react-pdf/renderer": "^4.5.1",