Does the emission of a white fluid -unnoticed or not accompanied by a wet dream or after intercourse- necessitate repeating the prayer, or performing ghusl, or only wudu', and is it considered maniy or madhiy?

What appears is that these discharges are normal vaginal secretions, which nullify ablution according to the Four Imams and others. The preponderant opinion is that they are pure.

It is recommended to treat them like pre-seminal fluid (madhiy), so you should wash them from the body and clothes. Whoever suffers from incontinence of these secretions should perform ablution for each prayer after its time has begun.