feat: add AI Prompts section, database model, public pages, and admin CRUD

prisma/schema.prisma

@@ -160,3 +160,15 @@ model Setting {
   value     String   @db.Text
   updatedAt DateTime @updatedAt
 }
+
+model Prompt {
+  id          String   @id @default(cuid())
+  title       String
+  slug        String   @unique
+  category    String
+  description String   @db.Text
+  content     String   @db.Text
+  tags        String[]
+  createdAt   DateTime @default(now())
+  updatedAt   DateTime @updatedAt
+}