Create the screen for users to create a new Bitcoin sell order. Tasks: - [x] Implement sell order creation form - [x] Create fiat currency selector for receiving - [x] Implement fiat amount field with range option - [x] Create accepted payment methods selector - [x] Implement market/fixed price toggle - [x] Implement slider for premium/discount adjustment - [x] Connect with addOrderNotifierProvider to send data - [x] Implement field validation - [x] Add cancel and submit buttons 
Create the screen for users to create a new Bitcoin sell order.
Tasks:
Implement sell order creation form
Create fiat currency selector for receiving
Implement fiat amount field with range option
Create accepted payment methods selector
Implement market/fixed price toggle
Implement slider for premium/discount adjustment
Connect with addOrderNotifierProvider to send data
Implement field validation
Add cancel and submit buttons