- Rename button "Fill amount" to "Pay order due amount" / "Plati dospjeli iznos ponude"
- Change button style from btn-link to btn-secondary for better visibility
- Fix @api.constrains to allow zero amount (prevents error on form save before action)
- Move positive amount validation to make_advance_payment method
- Update .pot and bs.po translations
🤖 assisted by claude
Adds a button next to "Order Due Amount" that fills the advance
amount with the full order due amount, converting currency if needed.
🤖 assisted by claude
