Shortcut to send transaction

### Is your feature request related to a problem?

The CLI provides a transaction builder, but sometimes after filling the fields of the TUI, we want to send the transaction.
But for now we have to tab back until the "Main" tab.
This is a bit annoying.

### Describe the solution you'd like

We should have a shortcut to send the transaction right away from any transaction builder tab, which will switch the view to the main tab, displaying the spinner and the final status.

### Additional context

_No response_

### Epic

_No response_

Start by locating the CLI's TUI transaction builder tabs and the Main tab's existing transaction-send flow. Trace how the spinner and final status are displayed, then identify how keyboard shortcuts switch views. Done means a shortcut from any transaction builder tab sends the transaction, switches to Main, and displays the spinner and final status.

Written by the indexing model from the issue text.