Add & use 30-day scope on snippet for update logs

This ensures that update logs are pinned as announcements for 30 days at most.

.vscode/spellright.dict

@@ -48,3 +48,4 @@ svg
 nowrap
 codepen
 inputmode
+updatelog

src/adapters/page/homePage.js

@@ -78,8 +78,12 @@ export default class HomePage extends Page {
     const latestUpdateLog = Snippet.scope(
       'updateLogs',
       'published',
-      'byNew'
-    ).first;
+      'byNew',
+      'last30Days'
+    )?.first;
+
+    if (!latestUpdateLog) return null;
+
     return {
       text: 'Read the latest update log:',
       linkText: latestUpdateLog.previewTitle,

src/models/snippet.js

@@ -35,6 +35,12 @@ export default class Snippet extends ContentModel {
     return records.order((a, b) => b.dateModified - a.dateModified);
   }
 
+  static last30Days(records) {
+    let date = new Date();
+    date.setDate(date.getDate() - 30);
+    return records.where({ dateModified: d => d > date });
+  }
+
   static published(records) {
     const now = new Date();
     return records.where({ dateModified: d => d < now });