add marker in feed to show where they've seen claims, plus other small clean-up

src/db/tables/settings.ts

@@ -1,10 +1,12 @@
 // a singleton
 export type Settings = {
   id: number; // there's only one entry: MASTER_SETTINGS_KEY
+
   activeDid?: string;
   apiServer?: string;
   firstName?: string;
   lastName?: string;
+  lastViewedClaimId?: string;
   showContactGivesInline?: boolean;
 };