Why is «يَا أَيُّهَا» madd munfaṣil?

Al-Kāfirūn and An-Naṣr: Applied Madd, Idghām, Ghunnah and Waqf

• Madd and hamzah occur in one word
• Madd ends one word; hamzah starts the next
• Sākin nūn is followed by tāʾ
• Sākin mīm is followed by bāʾ