Build Your Own Helpdesk

Build me a simple helpdesk/ticket system with the following specifications:

## Tech Stack
- Next.js 14 with App Router
- Prisma with PostgreSQL
- Tailwind CSS + shadcn/ui
- Resend for email

## Core Features

### 1. Ticket Management
- List all tickets with status filters (Open, Pending, Resolved, Closed)
- Ticket fields: subject, description, status, priority, assignee, customer email
- Create tickets via form or email (basic)
- Ticket detail view with full history

### 2. Conversation Thread
- Reply to tickets
- Internal notes (not visible to customer)
- Show full conversation history
- Rich text editor for responses

### 3. Assignment & Workflow
- Assign tickets to team members
- Change status and priority
- Add tags/categories
- Due date setting

### 4. Customer Portal (optional)
- Public ticket submission form
- Customer can view their tickets
- Customer can reply to tickets

### 5. Dashboard
- Open tickets count
- Average response time
- Tickets by status chart
- Recent activity

### 6. Notifications
- Email to customer when reply sent
- Email to agent when new ticket
- Email on assignment

## Database Schema
```prisma
model Ticket {
  id          String    @id @default(cuid())
  subject     String
  status      String    @default("open")
  priority    String    @default("medium")
  customerEmail String
  customerName  String?
  assigneeId  String?
  assignee    User?     @relation(fields: [assigneeId], references: [id])
  messages    Message[]
  tags        String[]
  createdAt   DateTime  @default(now())
  updatedAt   DateTime  @updatedAt
}

model Message {
  id        String   @id @default(cuid())
  ticketId  String
  ticket    Ticket   @relation(fields: [ticketId], references: [id])
  content   String
  authorId  String?
  author    User?    @relation(fields: [authorId], references: [id])
  isInternal Boolean @default(false)
  createdAt DateTime @default(now())
}
```

Please generate all files for a working helpdesk system.