Ctrl+mouse wheel does not zoom in text in Markdown previews (including the Agent panel)

Reproduction steps

1. Check zed://settings/mouse_wheel_zoom
2. Open an .md file in an editor
3. Hold Ctrl and roll the mouse wheel to confirm zooming
4. Preview the file as Markdown
5. Hold Ctrl and roll the mouse wheel

Current vs. Expected behavior

Current: no zoom (the preview / Agent thread scrolls instead)

Expected: zoom when zed://settings/mouse_wheel_zoom is on.

Zed version and system specs

Zed: v1.18.0+preview.348.0231e5db545bdf70c13f1b7c225034c05bb6c38e (Zed Preview)
OS: Linux Wayland ubuntu 26.04
Memory: 62.5 GiB
Architecture: x86_64
GPU: Intel(R) Iris(R) Xe Graphics (ADL GT2) || Intel open-source Mesa driver || Mesa 26.0.8-1ubuntu0.3

Relevant Zed settings

<details><summary>settings.json</summary>

<!-- Paste your settings inside the code block. -->


</details>