fix: remove shortTradeSize from default config and fix form handling

[cj4c0b1]

Description

• Removed from default config to prevent automatic addition
• Fixed form handling to properly respect trade size removal
• Updated validation to handle missing trade size fields gracefully

Related Issues

Closes CryptoGnome#45

Testing

• Verified that removing from config persists after restart
• Confirmed that form validation works as expected with and without separate trade sizes

Notes

This change ensures that the bot doesn't automatically add back the field when it's removed from the config.