refactor: remove setup feature from build exports and config

Removes the `./setup` export entry from `package.json` and the
corresponding `src/features/setup/index.js` entry point from
`tsup.config.js`, eliminating the standalone setup feature module
from the public API and build output.

package.json

@@ -123,9 +123,6 @@
     "./provider": {
       "import": "./dist/features/provider/index.js"
     },
-    "./setup": {
-      "import": "./dist/features/setup/index.js"
-    },
     "./core/modules": {
       "import": "./dist/core/modules/index.js"
     },