Tapping on an image opens pinch-to-zoom view

[amarek]

Some images embedded in articles become too small to see the details when viewed on a mobile/e-reader device. This change adds the capbility to open a zoomable view of an image by tapping on it. Tapping again closes the view.

Details:

• Adds an image-zoom handler (JS) that sends image URLs from the article WebView back to the app.
• New ImageViewActivity (PhotoView-based) opens a full-screen pinch-to-zoom viewer, loading from cache, file://, or network with downsample-to-4096px to avoid Canvas size crashes.
• Wires the JS interface and activity into ReadArticleActivity and the manifest.

[Strubbl]

Thank you, this would have fixed #616. But i do not want to add a dependency to an unmaintained lib (https://github.com/Baseflow/PhotoView). Last commit was 6 years ago, last tag/release ~8 years ago.