chore: downgrade Prisma to v6.19.3, remove redundant config files, and update schema datasource configurations

admin/package.json

@@ -9,9 +9,9 @@
     "lint": "eslint"
   },
   "dependencies": {
-    "@prisma/adapter-pg": "^7.7.0",
-    "@prisma/client": "^7.7.0",
-    "@prisma/config": "^7.7.0",
+    "@prisma/adapter-pg": "6.19.3",
+    "@prisma/client": "6.19.3",
+    "@prisma/config": "6.19.3",
     "@types/bcryptjs": "^2.4.6",
     "afrohub": "file:..",
     "bcryptjs": "^3.0.3",
@@ -19,7 +19,7 @@
     "lucide-react": "^1.8.0",
     "next": "16.2.3",
     "pg": "^8.20.0",
-    "prisma": "^7.7.0",
+    "prisma": "6.19.3",
     "react": "19.2.4",
     "react-dom": "19.2.4",
     "react-hot-toast": "^2.6.0",