refactor(schema): tighten public contracts (#33771)

packages/schema/src/vcs-event.ts

@@ -1,12 +1,13 @@
 export * as VcsEvent from "./vcs-event"
 
 import { Schema } from "effect"
+import { optional } from "./schema"
 import { Event } from "./event"
 
 export const BranchUpdated = Event.define({
   type: "vcs.branch.updated",
   schema: {
-    branch: Schema.optional(Schema.String),
+    branch: optional(Schema.String),
   },
 })