feat: Enhances image loading with lazy loading

Adds lazy loading attribute to images to improve page load
performance and user experience by deferring the loading
of images until they are in the viewport.

Fixes #44.

src/wikimore/app.py

@@ -428,6 +428,9 @@ def wiki_article(
     for img in soup.find_all("img"):
         img["src"] = get_proxy_url(img["src"])
 
+        # While we're at it, ensure that images are loaded lazily
+        img["loading"] = "lazy"
+
     for source in soup.find_all("source"):
         source["src"] = get_proxy_url(source["src"])