Make Lightning vs. Bitcoin actions more explicit

[LilChange]

Expected Behavior

Zap is a dead simple intuitive Lightning wallet for as many types of users as possible.

Actual Behavior

More confusing that is ideal to figure out how to add on-chain bitcoin to the wallet.

Possible Fix

The following is a proposed fix including:

• Gray bitcoin icon next to onchain amount
• UTF-8 icons for lightning bolts on Pay and Receive

Context

I spent about a minute clicking around after launching before I figured out how to get a normal BTC address. I tried clicking on Receive not realizing that is for Lightning only.