improve minSendableSats handling

[myxmaster]

Description

This fixes #2821.

Before, we were using lnurl.minSendable for amount only, but it's needed for satAmount also, since this is actually used for sending (amount is only used for displaying).

Additionally fixed another bug: When unit was set to ₿ or Fiat when scanning the lnurlp QR, lnurl.minSendable was used without conversion, resulting in ₿ 1 or $1.
Note: In Fiat case it will display $0.00 in Amount input now, which is correct, but also ₿0.00 000 000 and 0sats, which is wrong, because this conversion here uses the actual input $0.00. It still uses the correct satAmount (1) internally, so when user proceeds it works fine (see last screenshot), but of course we should think about how to handle this better, but not in this PR.

Before	After

It still uses 1sat, although displayed Amount was converted to 0sats in the view before:

This pull request is categorized as a:

• New feature
• Bug fix
• Code refactor
• Configuration change
• Locales update
• Quality assurance
• Other

Checklist

• I’ve run yarn run tsc and made sure my code compiles correctly
• I’ve run yarn run lint and made sure my code didn’t contain any problematic patterns
• I’ve run yarn run prettier and made sure my code is formatted correctly
• I’ve run yarn run test and made sure all of the tests pass

Testing

If you modified or added a utility file, did you add new unit tests?

• No, I’m a fool
• Yes
• N/A

I have tested this PR on the following platforms (please specify OS version and phone model/VM):

• Android
• iOS

I have tested this PR with the following types of nodes (please specify node version and API version where appropriate):

• Embedded LND
• LND (REST)
• LND (Lightning Node Connect)
• Core Lightning (CLNRest)
• Nostr Wallet Connect
• LndHub
• [DEPRECATED] Core Lightning (c-lightning-REST)
• [DEPRECATED] Core Lightning (Spark)
• [DEPRECATED] Eclair

Locales

• I’ve added new locale text that requires translations
• I’m aware that new translations should be made on the ZEUS Transfix page and not directly to this repo

Third Party Dependencies and Packages

• Contributors will need to run yarn after this PR is merged in
• 3rd party dependencies have been modified:
  • verify that package.json and yarn.lock have been properly updated
  • verify that dependencies are installed for both iOS and Android platforms

Other:

• Changes were made that require an update to the README
• Changes were made that require an update to onboarding

[shubhamkmr04]

tACK