I came across this while tackling another block map sync issue.
When a block is anchored past the point where its line soft wraps,
inserting or removing it invalidated the wrong range of rows. Inserting
such a block alone could silently not show it, and removing it could
leave the block on screen.
To reproduce:
```sh
SEED=113 ITERATIONS=1 cargo test -p editor test_random_blocks
```
Release Notes:
- Fixed inline assistant prompt sometimes not appearing, or lingering
after dismissal, when that line was soft-wrapped.
Smit Barmase
c3c589168b