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";

src/cli/cli.ts

@@ -7,7 +7,6 @@ import { basename, dirname, join, resolve } from "path";
 import { fileURLToPath } from "url";
 
 import { signMcpbFile, unsignMcpbFile, verifyMcpbFile } from "../node/sign.js";
-import { cleanMcpb, validateManifest } from "../node/validate.js";
 import { initExtension } from "./init.js";
 import { packExtension } from "./pack.js";
 import { unpackExtension } from "./unpack.js";