hark-store: give %read-all fact

Fixes urbit/landscape#402

pkg/arvo/app/hark-store.hoon

@@ -661,8 +661,7 @@
         unreads-each    (~(run by unreads-each) _~)      
         notifications  (~(run by notifications) _~)
       ==
-    =>  rebuild-cache
-    seen
+    (give:seen:rebuild-cache %read-all ~)
   ::
   ++  set-dnd
     |=  d=?

pkg/interface/src/logic/reducers/hark-update.ts

@@ -112,6 +112,14 @@ function reduce(data: any, state: HarkState) {
   unreadEach(data, state);
   seenIndex(data, state);
   removeGraph(data, state);
+  readAll(data, state);
+}
+
+function readAll(json: any, state: HarkState) {
+  const data = _.get(json, 'read-all');
+  if(data) { 
+    clearState(state);
+  }
 }
 
 function removeGraph(json: any, state: HarkState) {