Add setting for opting in to beta features (#11123)

src/storage/schema.ts

@@ -91,4 +91,16 @@ export type Account = {
    * Recently selected GIFs in the GIF picker. Most recent first, capped at 20.
    */
   recentGifs?: Gif[]
+
+  /**
+   * Cached from preferences (`bskyAppState.isBetaUser`) so the GrowthBook
+   * `isBetaUser` attribute can be set synchronously at analytics init, before
+   * beta-gated features (e.g. SearchV2Enable) are first evaluated. Written back
+   * when preferences load.
+   *
+   * Scoped per account, since `isBetaUser` is account-specific preference data.
+   * Reading it globally would let a beta account's value leak into a non-beta
+   * account after a switch, until that account's preferences loaded.
+   */
+  isBetaUser?: boolean
 }