[Feature]: Improve error when unable to top up spending balance due to max liquidity limit

[catch-21]

Describe the problem

When a user wants to transfer from savings to spending but are already very near to or have even exceeded the €950 limit they will get a message like:

It isn't clear what they can do to resolve the issue.

Describe the solution

We could suggest that they close one of their LN channels, perhaps the one with most inbound liquidity.

Additional context

No response

[catch-21]

Verified in v1.0.8
When it is not possible to transfer any more funds from savings to spending due to zero available liquidity, the error now reads "You've reached the maximum for your spending balance."
Where there is some available liquidity, it still gives the $ amount when attempting to exceed the maximum.