fix(tools): flatten nested anyOf schemas for Vertex AI compatibility

Claude API on Vertex AI (Cloud Code Assist) rejects nested anyOf schemas
as invalid JSON Schema draft 2020-12. This change:

- Add tryFlattenLiteralAnyOf() to convert Type.Union([Type.Literal(...)])
  patterns from anyOf with const values to flat enum arrays
- Update stringEnum helper in bash-tools to use Type.Unsafe with flat enum
- Flatten BrowserActSchema from discriminated union to single object
- Simplify TelegramToolSchema to use Type.String() for IDs

Fixes 400 errors when sending messages through WhatsApp/Telegram providers.

src/agents/tools/telegram-schema.ts

@@ -2,11 +2,14 @@ import { Type } from "@sinclair/typebox";
 
 import { createReactionSchema } from "./reaction-schema.js";
 
+// NOTE: chatId and messageId use Type.String() instead of Type.Union([Type.String(), Type.Number()])
+// because nested anyOf schemas cause JSON Schema validation failures with Claude API on Vertex AI.
+// Telegram IDs are coerced to strings at runtime in telegram-actions.ts.
 export const TelegramToolSchema = Type.Union([
   createReactionSchema({
     ids: {
-      chatId: Type.Union([Type.String(), Type.Number()]),
-      messageId: Type.Union([Type.String(), Type.Number()]),
+      chatId: Type.String(),
+      messageId: Type.String(),
     },
     includeRemove: true,
   }),