feat: add "Hello from the otter side" easter eggs

Custom 404 pages for landing and docs sites, otter greeting on the
first-login sidebar, and a one-time welcome toast after password change.

packages/shared/src/i18n/en.ts

@@ -1687,8 +1687,8 @@ export const en = {
     connectionError: "Connection error",
     changingButton: "Changing...",
     changeButton: "Change password",
-    sidebarTitle: "Almost there",
-    sidebarDescription: "Set a strong password to secure your account, then you are good to go.",
+    sidebarTitle: "Hello from the otter side!",
+    sidebarDescription: "Set a strong password to secure your account, then you're good to go.",
   },
   automate: {
     title: "Automate",