Cannot scroll code block

### Steps to reproduce

1. Have a codeblock like in a room:
```
user:~/work/element-web/apps/web (rav/device_listener *+$)$ pnpm exec tsc --noEmit
../../node_modules/.pnpm/matrix-js-sdk@https+++codeload.github.com+matrix-org+matrix-js-sdk+tar.gz+e16b0bcc06d0b17889f3eedef972f3cae9790f08/node_modules/matrix-js-sdk/src/embedded.ts:320:65 - error TS2339: Property 'MSC4533RtcLivekitGetToken' does not exist on type 'typeof MatrixCapabilities'.

320 this.widgetApi.requestCapability(MatrixCapabilities.MSC4533RtcLivekitGetToken);
~~~~~~~~~~~~~~~~~~~~~~~~~

../../node_modules/.pnpm/matrix-js-sdk@https+++codeload.github.com+matrix-org+matrix-js-sdk+tar.gz+e16b0bcc06d0b17889f3eedef972f3cae9790f08/node_modules/matrix-js-sdk/src/embedded.ts:323:65 - error TS2339: Property 'MSC4533RtcLivekitDelegateDelayedLeave' does not exist on type 'typeof MatrixCapabilities'.

323 this.widgetApi.requestCapability(MatrixCapabilities.MSC4533RtcLivekitDelegateDelayedLeave);
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

```

### Outcome

#### What did you expect?

The codeblock should be scrollabke, and the copy icon is visible.

#### What happened instead?

The codeblock is "slightly" scrollable, and no icons are visible.

### Operating system

Arch Linux

### Application version

Element Nightly version: 2026083101 Crypto version: Rust SDK 0.18.0 (16a138b), Vodozemac 0.10.0

### How did you install the app?

AUR

### Homeserver

half-shot.uk

### Will you send logs?

No

Reproduce the issue in an Element room using the supplied long TypeScript error code block. Inspect the code-block rendering entry point and compare its overflow behavior and copy-icon visibility with the expected scrollable block; done means long blocks scroll normally and the copy icon is visible.

Written by the indexing model from the issue text.