Turkish currency format update

Display format used by the software:
100        => 100,00 ₺
1250.50    => 1.250,50 ₺
12500.50   => 12.500,50 ₺
Quantity   => 1.250

Important:
- Database/calculation values remain normal decimal values, for example 1250.50.
- Visible values are displayed in Turkish format, for example 1.250,50 ₺.
- Product price/tax inputs now accept Turkish comma decimals like 33,75 and save them safely as 33.7500.
- Run database_turkish_currency_fix.sql once on the database after uploading this code.
