Remove all console.log, console.warn, and console.error statements
that were added for debugging in article cache, service worker,
and image caching code.
With injectManifest strategy, the Service Worker needs to be built, so it's
not available in dev mode. To enable testing image caching in dev, we now:
1. Created public/sw-dev.js - a simplified SW that only handles image caching
2. Updated registration to use sw-dev.js in dev mode, sw.js in production
3. Dev SW uses simple cache-first strategy for images
This allows testing image caching in development without needing a build.
