Prompt

Convert web app to Progressive Web App.

<current_app>
{existing web application details}
</current_app>

<offline_requirements>
{offline functionality needs}
</offline_requirements>

<target_devices>
{mobile/desktop targets}
</target_devices>

Implement:
1. Service worker strategy
2. Caching approach
3. Offline functionality
4. Push notifications
5. App manifest
6. Installation flow