Add canvas: false webpack alias to fix browser build

The canvas module is a server-side dependency used by prismarine-viewer
(in entities.js and atlas.js). In browser builds, the native Canvas API
is available instead. Adding canvas: false to webpack aliases prevents
the "Module not found: Error: Can't resolve 'canvas'" build failure.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: rom1504

webpack.common.js

@@ -22,7 +22,8 @@ const config = {
       net: 'net-browserify',
       fs: false,
       jose: false,
-      '@azure/msal-node': false
+      '@azure/msal-node': false,
+      canvas: false
     },
     fallback: {
       jose: false,