[feature] Inform users that small payments are likely to fail with "no route"

[MegalithicBTC]

Currently, Blink won't pay a route if the total fee exceed .5% of the payment amount. This is understandable logic to protect Blink users from excessive fees.

But: because most of the network uses LND and CLN's default fees (see https://github.com/lightningnetwork/lnd/blob/8ecef03315f749ae8820b4735978ca2e0552de2e/sample-lnd.conf#L685 ) of 1000 msats (1 sat), this means that a user using Blink to send 1 satoshi, or 5 satoshis, or 10 satoshis, is likely to find that their payment fails with "no route".

Again, not supporting small payments with Blink is a legitimate design decision, perhaps Blink is designed only for real-world use and not for micropayments, Nostr, Zaps, or etc.

But the problem is that a constant stream of Blink users are coming to other services/wallets and complaining of "no route"..... A simple notice for users like "Payments under 1000 satoshis may fail" could solve this......

As an alternative, Blink could enable the wallet for modern usages like Nostr Zaps, using logic like max(0.5% of payment, 2 satoshis) for establishing a maximum fee payable.

[MegalithicBTC]

This could be useful, to see how LND does this by default: https://github.com/lightningnetwork/lnd/blob/8ecef03315f749ae8820b4735978ca2e0552de2e/lnwallet/parameters.go#L31

[MegalithicBTC]

To add more color to this. We are able to reproduce the issue by attempting to send payments of 300 satoshis and below. Payments of 301 Satoshis reliably succeed.

So in order to use Blink for zaps or other small payments, there would I think have to be a route where the fixed fees (base fee) on the entire route were no more than 1 satoshi... if there are two intermediary nodes, which EACH have a fixed fee of 1 satoshi (for example two LND or CLN nodes which were started with their default settings), and the payment amount is under 301 satoshis, then the payment will fail.