🔥 Drop redundant main/types fields

exports already declares types + import for the root entry, so the
top-level main/types pair was duplicate metadata. publint and attw stay
green with exports alone, verified against a packed consumer install.

package.json

@@ -27,8 +27,6 @@
     ],
     "type": "module",
     "sideEffects": false,
-    "main": "./dist/index.js",
-    "types": "./dist/index.d.ts",
     "exports": {
         ".": {
             "types": "./dist/index.d.ts",