GUI: Add coins tab and sets view-only mode
Adds Coins (UTXOs) tab at the top and:
- Removes selection checkboxes from the dialog
- Disables coin selection functionality
- Maintains UTXO viewing capabilities
- Removes all the information from the top area of the dialog.
The following pictures depict how the GUI would look like:
<img width="1082" height="705" alt="coins_1" src="https://github.com/user-attachments/assets/939e6b11-cb88-4662-bc11-adead54675c3" />
<img width="1128" height="829" alt="coins_3" src="https://github.com/user-attachments/assets/8cd26db3-bd20-4cbd-953e-6b63da99d05a" />