chore: add deprecation notice on dot org site

packages/web/src/javascripts/Components/ApplicationView/DotOrgNotice.tsx

@@ -0,0 +1,16 @@
+import { FunctionComponent } from 'react'
+
+const DotOrgNotice: FunctionComponent = () => {
+  return (
+    <div className="align-center z-modal flex h-30 w-full w-full items-center bg-danger text-center text-info-contrast">
+      <div className="w-full text-center text-xl font-bold">
+        app.standardnotes.org is no longer maintained. Please switch to{' '}
+        <a className="underline" href="https://app.standardnotes.com">
+          app.standardnotes.com
+        </a>
+      </div>
+    </div>
+  )
+}
+
+export default DotOrgNotice