Aegis: load the DigiByte deps module as ESM in a dev checkout

lib/dgb/deps.js is ESM, but in a dev checkout the nearest package.json
is TheseusNavigator's, which says "type": "commonjs"; the import threw
and DigiByte was silently unavailable whenever Theseus ran from the
repo. Shipped installs have no package.json above the add-on, so they
were unaffected. lib/dgb/core and lib/dgb/psbt already carry the same
marker.

lib/dgb/package.json

@@ -0,0 +1 @@
+{"type":"module"}