Fix border-radius on view, blame and code search (#30545)

Fix border-radius on view, blame and code search (#30545)

Fixes: https://github.com/go-gitea/gitea/issues/30540
1. Fix all these boxes by adding `bottom attached` and removing a
problematic CSS rule:

<img width="1319" alt="Screenshot 2024-04-17 at 22 25 31"
src="https://github.com/go-gitea/gitea/assets/115237/346445a4-4944-4003-a1ef-6f5b0eda624e">
<img width="643" alt="Screenshot 2024-04-17 at 22 21 18"
src="https://github.com/go-gitea/gitea/assets/115237/10f17ed3-9ad6-48de-92fa-bac6621815b9">

2. Change the "last commit" box to `ui segment` which has correct
border-radius. Also included is a tiny tweak to make author name ellipse
instead of wrap.

<img width="1331" alt="Screenshot 2024-04-17 at 22 23 23"
src="https://github.com/go-gitea/gitea/assets/115237/285fbd45-ced0-4d33-abe3-7384ffa03188">

Co-authored-by: Giteabot <teabot@gitea.io>