Add Progressive Web App (PWA) support for offline reading #174
Description
The "What Is Code?" article is a long-form, text-heavy piece that users would benefit from reading offline. Currently, there's no offline support, making it impossible to read the article without an internet connection.
Proposed enhancement:
Implement Service Workers for offline caching
Add a web manifest file for PWA capabilities
Cache essential assets (HTML, CSS, JS, images) for offline access
Show offline indicator when network is unavailable
Allow users to "Save for offline reading"