shelduck got simpler: debts by person, picking people from Telegram and debts in any chat

We've reworked the bot so that anyone can figure it out: less text, more buttons.
Debts — by person
The Debts screen now shows your totals and a list of people. Tap a person to open their card with every action: “I got it back”, “Remind”, “Pay back all”, “Pay back part”. Only the buttons that fit are shown.
Pick a person right from Telegram
When adding a debt, tap “Choose a person” at the bottom — your Telegram contacts open. No need to know anyone's @username anymore. If the person isn't on shelduck yet, the bot prepares an invite.
A debt in any chat
Type @shelduck_bot 20 pizza in a chat — a card appears, and the other person confirms the debt with one tap. You can send an invite to the right chat with the “Send to a chat” button.
In groups — only for you
The /debts and /help commands in a group answer so that only you see the reply: your debts stay private.
10 languages
The bot speaks Russian, Ukrainian, English, German, Polish, Portuguese, Romanian, Uzbek, Hindi and Hebrew.