chore: update package.json metadata

Rename package to "grain", mark as private, and change license to Apache-2.0

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <[e-mail]>

package.json

···
 {
-  "name": "grain-next",
+  "name": "grain",
   "version": "1.0.0",
+  "private": true,
   "description": "",
   "main": "index.js",
   "directories": {
···
   },
   "keywords": [],
   "author": "",
-  "license": "ISC",
+  "license": "Apache-2.0",
   "dependencies": {
     "@fortawesome/fontawesome-free": "^7.1.0",
     "lit": "^3.3.2",