Add onboarding (WIP)

src/state/lib/type-guards.ts

@@ -8,3 +8,7 @@ export function hasProp<K extends PropertyKey>(
 ): data is Record<K, unknown> {
   return prop in data
 }
+
+export function isStrArray(v: unknown): v is string[] {
+  return Array.isArray(v) && v.every(item => typeof item === 'string')
+}