UX: Misc Improvements

[kilrau]

• Main idea: "Instructions as titles" as previously done in Figma
• ~Orignal issue: https://github.com/BoltzExchange/boltz-web-app/issues/220~
• Additional things to consider: show preimage as proof of Payment for Normal swaps? See discussion at https://discord.com/channels/547454030801272832/714342346568892487/1164762317439914085
• ~Send to for paying a ln invoice sounds just wrong, copy button is missing -> not discoverable one can click to copy the invoice~
• ~Move denomination swtich to upper right to be present whenever therer are amounts just like in PRD~
• "locked amount is less than expexted amount" -> "you sent amount too little"
• Include still releveant and missing things from PRD
• add "sats/btc" after all amounts, still missing in some pages
• make clear reverse swaps are automatically refunded, add invoice expiry as estimated time
• ~people don't get the refund page~