TASK: Create the shared domain package.

Domain Details:

## 1. Core Domain Logic

### 1.1 Domain Entities Overview

The KROW platform has **49 domain entities** organized into 8 logical groups:

```
┌────────────────────────────────────────────────────────────────────┐
│                        KROW DOMAIN MODEL                           │
├────────────────────────────────────────────────────────────────────┤
│                                                                    │
│  ┌─────────────┐    ┌─────────────┐    ┌─────────────┐             │
│  │   USERS &   │    │  BUSINESS & │    │  EVENTS &   │             │
│  │ MEMBERSHIP  │    │ ORGANIZATION│    │   SHIFTS    │             │
│  ├─────────────┤    ├─────────────┤    ├─────────────┤             │
│  │ User        │    │ Business    │    │ Event       │             │
│  │ Staff       │    │ BusinessSet │    │ EventShift  │             │
│  │ Membership  │    │ Hub         │    │ Position    │             │
│  │ BizMember   │    │ HubDept     │    │ Assignment  │             │
│  │ HubMember   │    │ BizContract │    │ WorkSession │             │
│  └─────────────┘    └─────────────┘    └─────────────┘             │
│                                                                    │
│  ┌─────────────┐    ┌─────────────┐    ┌─────────────┐             │
│  │  SKILLS &   │    │  FINANCIAL  │    │  RATINGS &  │             │
│  │   CERTS     │    │   PAYROLL   │    │  PENALTIES  │             │
│  ├─────────────┤    ├─────────────┤    ├─────────────┤             │
│  │ Skill       │    │ Invoice     │    │ StaffRating │             │
│  │ SkillCat    │    │ InvoiceItem │    │ PenaltyLog  │             │
│  │ StaffSkill  │    │ InvDecline  │    │ BizStaffPref│             │
│  │ Certificate │    │ StaffPayment│    │             │             │
│  │ SkillKit    │    │             │    │             │             │
│  └─────────────┘    └─────────────┘    └─────────────┘             │
│                                                                    │
│  ┌─────────────┐    ┌─────────────┐                                │
│  │   STAFF     │    │   SUPPORT   │                                │
│  │   PROFILE   │    │    CONFIG   │                                │
│  ├─────────────┤    ├─────────────┤                                │
│  │ EmergencyC  │    │ Addon       │                                │
│  │ BankAccount │    │ Tag         │                                │
│  │ Accessibl   │    │ Media       │                                │
│  │ Schedule    │    │ WorkingArea │                                │
│  └─────────────┘    └─────────────┘                                │
│                                                                    │
└────────────────────────────────────────────────────────────────────┘
```

### 1.2 Key Entity Definitions

#### User & Authentication

| Entity | Description | Key Fields |
|--------|-------------|------------|
| **User** | Base auth entity (Firebase) | `id`, `email`, `phone`, `role` |
| **Staff** | Worker profile | `auth_provider_id`, `name`, `email`, `phone`, `status`, `address`, `avatar`, `live_photo` |
| **Membership** | Polymorphic org membership | `user_id`, `memberable_id`, `memberable_type`, `role` |

**Staff Status Flow:**
```
registered → pending → completed_profile → verified → [active | blocked | inactive]
```

#### Business & Organization

| Entity | Description | Key Fields |
|--------|-------------|------------|
| **Business** | Client company | `name`, `registration`, `status`, `avatar` |
| **BusinessSetting** | Payroll config | `prefix`, `overtime`, `clock_in`, `clock_out` |
| **Hub** | Branch location | `business_id`, `name`, `address`, `status` |
| **HubDepartment** | Dept within hub | `hub_id`, `name` |

#### Events & Shifts

| Entity | Description | Key Fields |
|--------|-------------|------------|
| **Event** | Job posting | `business_id`, `hub_id`, `name`, `date`, `status`, `contract_type` |
| **EventShift** | Work session | `event_id`, `name`, `address` |
| **EventShiftPosition** | Job opening | `shift_id`, `skill_id`, `count`, `rate`, `start_time`, `end_time`, `break` |
| **EventShiftPositionStaff** | Assignment | `staff_id`, `position_id`, `status`, `clock_in`, `clock_out` |

**Event Status Flow:**
```
draft → pending → assigned → confirmed → active → finished → completed → closed
                                                           ↘ under_review
```

**Assignment Status Flow:**
```
assigned → confirmed → ongoing → completed
         ↘ decline_by_staff → [penalty logged]
         ↘ canceled_by_staff → [penalty logged]
         ↘ no_showed → [penalty logged]
```

#### Skills & Certifications

| Entity | Description | Key Fields |
|--------|-------------|------------|
| **Skill** | Job category | `category_id`, `name`, `price` |
| **StaffSkill** | Worker qualification | `staff_id`, `skill_id`, `level`, `experience`, `status` |
| **Certificate** | Required credential | `name`, `required` |
| **SkillKit** | Uniform/equipment req | `skill_id`, `name`, `is_required`, `type` |

**Skill Levels:** `beginner` | `skilled` | `professional`

#### Financial & Payroll

| Entity | Description | Key Fields |
|--------|-------------|------------|
| **Invoice** | Business bill | `event_id`, `business_id`, `status`, `total`, `work_amount`, `addons_amount` |
| **InvoiceItem** | Line item | `invoice_id`, `staff_id`, `work_hours`, `rate`, `amounts` |
| **StaffPayment** | Worker payout | `staff_id`, `assignment_id`, `amount`, `status`, `paid_at` |

**Invoice Status Flow:**
```
open → disputed → resolved → verified → paid/reconciled
     ↘ overdue
```

### 1.3 Core Business Workflows

#### Workflow 1: Event Lifecycle

```mermaid
sequenceDiagram
    participant Client as Client App
    participant API as Backend API
    participant Admin as Admin
    participant Staff as Worker App

    Note over Client,API: 1. Event Creation
    Client->>API: Create Event with Shifts & Positions
    API-->>Client: Event Created (Draft)
    Client->>API: Publish Event
    API-->>Client: Event Published

    opt 2. Staff Assignment (Optional)
        Note over Admin,API: Optional Staff Assignment
        Admin->>API: Assign Staff to Shift
        API-->>Admin: Assignment Confirmed
        API->>Staff: Notification: New Shift
    end

    Note over Staff,API: 3. Shift Acceptance
    Staff->>API: Accept Shift
    API-->>Staff: Shift Confirmed

    Note over Client,Staff: 4. Day of Event
    Client->>Client: Generate QR Code
    Staff->>Staff: Scan QR Code
    Staff->>API: Clock In
    Staff->>API: Clock Out

    Note over Client,API: 5. Post-Event
    Client->>API: Rate Staff
    API->>API: Generate Invoice
    Client->>API: Approve Invoice

```

#### Workflow 2: Staff Onboarding

```
1. Registration (Firebase Phone Auth)
   ├── Create Staff record (status: registered)
   └── Profile created with auth_provider_id

2. Profile Completion
   ├── Personal info (name, email, address)
   ├── Avatar upload
   ├── Emergency contacts
   └── Bank account details

3. Skills Declaration
   ├── Add skills with level/experience
   └── Status: pending → verified (admin)

4. Certification Upload
   ├── Upload certificates
   └── Status: pending → verified (admin)

5. Equipment Confirmation
   ├── Confirm uniforms per skill
   ├── Confirm equipment per skill
   └── Upload photos as proof

6. Profile Submission
   ├── Complete verification checklist
   └── Status: completed_profile → verified
```

#### Workflow 3: Payroll Calculation

```
Work Hours = (clock_out - clock_in) - break_duration

Overtime Rules:
├── Regular Hours (1x):     hours <= 8
├── Overtime Hours (1.5x):  8 < hours <= 10
└── Doubletime Hours (2x):  hours > 10

Payment = (regular_hours × rate × 1.0)
        + (overtime_hours × rate × 1.5)
        + (doubletime_hours × rate × 2.0)
        + addons_amount
```

You must:
1. Create domain entities for ALL KROW entities provided
2. Group entities by logical folders
3. Use immutable models
4. Do NOT add JSON, serialization, or Firebase annotations
5. Do NOT add business logic
6. Use enums for all status flows
7. Add Doc comments for readability of the code.

Entities MUST match:
- Names
- Fields
- Status flows

Include:
- Enums for status flows
- Value objects where appropriate
- Clear folder structure

Exclude:
- DTOs
- Repositories
- Firebase logic
- Validation logic

Create packages/domain/lib/domain.dart (barrel file)
This file must export ALL entities and enums.

All other packages will import ONLY:
import 'package:domain/domain.dart';

Must follow archtiecture principles defined in:
- docs/01-architecture-principles.md

Must Follow Agent rules defined in:
- docs/02-agent-development-rules.md

Output:
- Folder structure
- Dart files
- Short explanation of grouping strategy