WhatsApp QR and URL Generator


#### Description

Add a generator that accepts a phone number and optional message template and produces:

- A QR code
- A copyable URL using the `https://wa.me/<number>?text=<encoded_message>` format

#### Acceptance Criteria

- Phone number input is mandatory  
- Message template input is optional  
- QR code updates dynamically  
- Copyable URL is shown below the QR code