fix: add type:module and exports field to resolve ESM/CJS CI failures

vitest 4.x requires ESM context to load its config. Without "type": "module",
Node 18.x fails with ERR_REQUIRE_ESM when vitest/dist/config.cjs tries to
require std-env (an ESM-only package). Adding "type": "module" makes vitest
load the config as ESM and also aligns the dist output (now proper ESM exports)
with the tsconfig NodeNext module mode. Added an exports field for correct
package resolution by modern bundlers and Node.js.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: Zie619

package.json

@@ -2,8 +2,15 @@
   "name": "trusera-sdk",
   "version": "0.1.0",
   "description": "TypeScript SDK for monitoring AI agents with Trusera - intercept HTTP, evaluate policies",
+  "type": "module",
   "main": "dist/index.js",
   "types": "dist/index.d.ts",
+  "exports": {
+    ".": {
+      "import": "./dist/index.js",
+      "types": "./dist/index.d.ts"
+    }
+  },
   "license": "Apache-2.0",
   "repository": {
     "type": "git",