added username (models.CharField) & searchable (models.BooleanField) to User model in lyric app; new ITs confirm functionality here; dashboard views now ensure that sharing a list w. an email address (as opposed to a username) neither confirms nor denies whether that email address has a registered account (ITs green)

src/apps/dashboard/views.py

@@ -1,3 +1,4 @@
+from django.contrib import messages
 from django.http import HttpResponseForbidden
 from django.shortcuts import redirect, render
 
@@ -56,4 +57,5 @@ def share_list(request, list_id):
         our_list.shared_with.add(recipient)
     except User.DoesNotExist:
         pass
+    messages.success(request, "An invite has been sent if that address is registered.")
     return redirect(our_list)