Enhance handleContactVisibility to return both title and message

Modified handleContactVisibility method to return structured notification data
with both title and message properties instead of just a string message.
Updated addContact method to use notify.toast() with custom title and message
from notification constants, providing more specific user feedback when
contacts are added with or without visibility settings.

src/libs/crypto/vc/index.ts

@@ -16,11 +16,11 @@ const u8a = {
   toString: (bytes: Uint8Array, encoding: string): string => {
     if (encoding === "base16") {
       return Array.from(bytes)
-        .map(b => b.toString(16).padStart(2, '0'))
-        .join('');
+        .map((b) => b.toString(16).padStart(2, "0"))
+        .join("");
     }
     throw new Error(`Unsupported encoding: ${encoding}`);
-  }
+  },
 };
 
 import { didEthLocalResolver } from "./did-eth-local-resolver";