The narration reports a matter of the unseen. لَا تَدْخُلُ الْمَلَائِكَةُ plainly means “angels do not enter.” Angels have different functions; the angels meant here are understood as angels of mercy.
The statement should be read according to its wording and scope. A short selected narration alone is not a complete treatment of every possible legal circumstance involving images or dogs.
تَصَاوِيرُ is the plural of صُورَةٌ (“image”). وَلَا links the second negative element to the first.