Remove instant scale(1.05) hover on attachment gallery items

Summary

On the feed page, hovering over non-image attachments (e.g. *.pdf boxes like on the post 'Pravda of pravda, the pravda') causes the attachment boxes to rapidly change size by a small margin (visible flicker/jitter). Cause is CSS rule .attachment-gallery-item:hover { transform: scale(1.05); } with transition: all 0s ease 0s. Measured box growth: 240x101.5 to 252x106.6 (~5% jump). Hovering near the box edge toggles hover on/off rapidly, which reads as flickering. Image attachments are affected by the same rule but it is visually masked because their fixed-size img fills a clipped frame (max-width 240px / max-height 200px, overflow hidden). PDF boxes (a.non-image with icon + filename + size) have no such clipped frame, so the whole visible box grows.

Steps to Reproduce

1. Go to /feed?tab=recent
2. Find the post 'Pravda of pravda, the pravda'
3. Mouse over the *.pdf attachment boxes near their edges
4. Observe the boxes rapidly changing size by a small margin

Expected Behaviour

Not provided.

Actual Behaviour

Attachment boxes rapidly change size by a small margin on hover near edges.

Environment

Not provided.

Reported by D-04got10-01 via DevPlace.