Remove validate utilities from browser exports

This removes the validateManifest utilities that were added to the browser bundle. These functions are not needed for the browser export.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: joan-anthropic

src/browser.ts

@@ -1,5 +1,4 @@
 // Browser-compatible exports
 export * from "./schemas/index.js";
-export * from "./schemas/validate.js";
 export * from "./shared/config.js";
 export * from "./types.js";