Implement proper CORS configuration for secure cross-origin usage

- Add flask-cors dependency and configure CORS with security best practices
- Support configurable CORS origins via environment variables
- Separate admin endpoint CORS configuration for enhanced security
- Create comprehensive CORS configuration documentation
- Add apiClient utility for CORS-aware frontend requests
- Include CORS test page for validation
- Update README with CORS configuration instructions

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

README.md

@@ -64,6 +64,20 @@ A mobile-friendly web application that translates spoken language between multip
 - Ollama provides access to the Gemma 3 model for translation
 - OpenAI Edge TTS delivers natural-sounding speech output
 
+## CORS Configuration
+
+The application supports Cross-Origin Resource Sharing (CORS) for secure cross-origin usage. See [CORS_CONFIG.md](CORS_CONFIG.md) for detailed configuration instructions.
+
+Quick setup:
+```bash
+# Development (allow all origins)
+export CORS_ORIGINS="*"
+
+# Production (restrict to specific domains)
+export CORS_ORIGINS="https://yourdomain.com,https://app.yourdomain.com"
+export ADMIN_CORS_ORIGINS="https://admin.yourdomain.com"
+```
+
 ## Mobile Support
 
 The interface is fully responsive and designed to work well on mobile devices.