Unify the display name fallback behavior

src/state/models/feeds/custom-feed.ts

@@ -1,6 +1,7 @@
 import {AppBskyFeedDefs, AtUri} from '@atproto/api'
 import {makeAutoObservable} from 'mobx'
 import {RootStoreModel} from 'state/models/root-store'
+import {sanitizeDisplayName} from 'lib/strings/display-names'
 
 export class CustomFeedModel {
   // data
@@ -34,6 +35,13 @@ export class CustomFeedModel {
     return this.data.uri
   }
 
+  get displayName() {
+    if (this.data.displayName) {
+      return sanitizeDisplayName(this.data.displayName)
+    }
+    return `Feed by @${this.data.creator.handle}`
+  }
+
   get isSaved() {
     return this.data.viewer?.saved
   }