[enh] Sandbox: keep `pubkey` + add `issuer` control

app/lib/dal/sqliteDAL/DocumentDAL.ts

 export interface DBDocument {
-  issuers: string[];
+  pubkey?: string
+  issuer?: string
+  issuers?: string[]
 }
\ No newline at end of file

app/lib/dal/sqliteDAL/SandBox.ts

@@ -13,7 +13,9 @@ export class SandBox<T extends DBDocument> {
   }
   
   async acceptNewSandBoxEntry(element:T, pubkey:string) {
-    if (element.issuers !== undefined && element.issuers.indexOf(pubkey) !== -1) {
+    if (element.pubkey === pubkey
+      || element.issuer === pubkey
+      || (element.issuers !== undefined && element.issuers.indexOf(pubkey) !== -1)) {
       return true;
     }
     const elements = await this.findElements()