Hyperlinks are not spoilered in the UI

[olivia-fl]

Describe the bug

With spoiler tags that contain links, the link is rendered visibly when the spoiler is unexpanded, even though the text is not.

Example:

Reproduction

1. send a message with markup ||some text https://example.com||
2. the unexpanded spoiler does not show "some text", but shows "https://example.com"

Expected behavior

All spoiler contents should be hidden when the spoiler is unexpanded.

Platform and versions

1. OS: Linux (NixOS)
2. Browser: Firefox 133.0
3. Cinny version: v4.2.3 (app.cinny.in)
4. Matrix homeserver: computer.surgery

Additional context

No response