docs(ai): improve onboarding steps and enforce node version

- Added `engines` field to `package.json` to enforce Node.js >=22.
- Updated `CONTRIBUTING.md` to specify prerequisites and clarify build commands.
- Created `ONBOARDING_REPORT.md` with audit findings.

Co-authored-by: PR0M3TH3AN <[email protected]>

package.json

@@ -3,6 +3,9 @@
   "private": true,
   "type": "module",
   "version": "1.0.0",
+  "engines": {
+    "node": ">=22"
+  },
   "scripts": {
     "start": "npm run build && npx serve dist",
     "serve": "npx serve",