Boost Carousel flipping backward

**Describe the bug**
Sometime in the past few days, the Boost carousel does this: I leave my mouse over the right arrow and tap-tap-tap my way through the boosted posts, carousel clicks left with each tap, but then sometimes (it's inconsistent) the carousel jumps way back to the right, to the first boost). It seems that leaving more time between taps minimizes (but doesn't eliminate) this behavior.

A clear and concise description of what the bug is.
- Which site: [e.g. dev.phanpy.social OR phanpy.social]
phanpy.social
- Which instance: [e.g. mastodon.social]
cosocial.ca

**Desktop (please complete the following information):**
- OS: [e.g. iOS] MacOS
- Browser [e.g. chrome, safari]: Safari
- Version [e.g. 22]: Version 17.0 (19616.1.27.211.1)

**Smartphone (please complete the following information):**
[not observed on my Pixel]

Reproduce the issue on phanpy.social using Safari 17 on macOS, moving through Boost posts with rapid repeated clicks on the right arrow. Trace the carousel implementation and its click or transition handling; done means repeated forward clicks no longer jump back to the first boost, including under rapid tapping.

Written by the indexing model from the issue text.