add the hashed-next-key to the contact data, shown & stored

src/db/tables/contacts.ts

@@ -1,11 +1,12 @@
 export interface Contact {
   did: string;
   name?: string;
+  nextPublicKeyHashBase64?: string; // base64-encoded SHA256 hash of next public key
   publicKeyBase64?: string;
   seesMe?: boolean;
   registered?: boolean;
 }
 
 export const ContactSchema = {
-  contacts: "&did, name", // no need to key by publicKeyBase64, registered, seesMe
+  contacts: "&did, name", // no need to key by other things
 };