Revert workerd/worker exports to ESM

The UMD bundle references browser globals (e.g. `window` in js-sha256)
that throw `ReferenceError: window is not defined` in the workerd
runtime. ESM was the working path before d856796; restoring it.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: luke-owen-crowdhandler

package.json

@@ -17,8 +17,8 @@
   "exports": {
     ".": {
       "types": "./dist/types/index.d.ts",
-      "workerd": "./dist/crowdhandler.umd.js",
-      "worker": "./dist/crowdhandler.umd.js",
+      "workerd": "./dist/crowdhandler.esm.js",
+      "worker": "./dist/crowdhandler.esm.js",
       "browser": "./dist/crowdhandler.umd.js",
       "import": "./dist/crowdhandler.esm.js",
       "require": "./dist/crowdhandler.cjs.js",