chore: isolate frontend and backend via npm workspaces and @mmapp/contracts

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

package.json

@@ -2,13 +2,18 @@
   "name": "mmapp",
   "version": "0.1.0",
   "private": true,
+  "workspaces": [
+    "packages/*",
+    "backend"
+  ],
   "scripts": {
     "dev": "next dev",
-    "build": "next build",
+    "build": "npm run build -w @mmapp/contracts && next build",
     "start": "next start",
     "lint": "eslint"
   },
   "dependencies": {
+    "@mmapp/contracts": "0.1.0",
     "@base-ui/react": "^1.4.1",
     "class-variance-authority": "^0.7.1",
     "clsx": "^2.1.1",