Why is the article lām assimilated in الصَّالِحَاتِ?

Al-ʿAṣr and At-Takāthur: Applied Ghunnah, Madd, Lām and Waqf

• Ṣād is a solar letter
• Ṣād is lunar
• There is no madd alif
• It has tāʾ marbūṭah