perf: less animation on toot expand?

**Describe the bug**

When I click on a toot, it expands on the right hand-side of the screen.

On my old thinkpad, this animation is slow and glitchy.

https://github.com/cheeaun/phanpy/assets/1991377/76895be1-b24d-4a38-9328-95d1442418b4

**To Reproduce**
1. Have an old laptop
2. Use phanpy

**Expected behavior**

Smooth operation on old hardware.

**Desktop (please complete the following information):**
- OS: Debian 12
- Browser: Chrome
- Version: Latest

Start by reproducing toot expansion in Chrome on the reported Debian 12 setup and identify the animation path used when a toot opens on the right-hand side. Compare behavior on older hardware and verify that the expansion is smooth without changing the expected interaction.

Written by the indexing model from the issue text.