Nextcloud Assistant behaves differently in the app than on the web

### ⚠️ Before posting ⚠️

- [x] This is a **bug**, not a question or an enhancement.
- [x] I've [searched for similar issues](https://github.com/nextcloud/android/issues) and didn't find a duplicate.
- [x] I've written a clear and descriptive title for this issue, not just "Bug" or "Crash".
- [x] I agree to follow Nextcloud's [Code of Conduct](https://nextcloud.com/contribute/code-of-conduct/).

### Steps to reproduce

1. Setup a self hosted LLM with an OpenAI compatible API and with thinking support; e.g. Qwen3 on vLLM
2. Setup Nextcloud Assistant at `/settings/admin/ai` to use the previously configured LLM
3. Make sure you prefix all prompt templates at `/settings/admin/ai` with `/no_think` to disable thinking
4. Use the rephrasing feature of Nextcloud Assistant. The same input in the Nextcloud app produces a different result than the input in the web UI. The app outputs `....` which indicates that thinking is disabled whereas the web UI doesn't output ``.

result on the web UI

result in the Nextcloud app

### Expected behaviour

Nextcloud Assistant on the web behaves the same as the Nextcloud Assistant in the app

### Actual behaviour

The Nextcloud Assistant on the mobile app triggers the thinking mode of the LLM.

I admit that I don't know if the web UI is just smarter stripping out the LLM thinking tag or if the web UI really doesn't use thinking because it obeys the configuration `/settings/admin/ai`.

### Android version

16

### Device brand and model

Pixel 9 Pro

### Stock or custom OS?

Stock

### Nextcloud android app version

3.34.1

### Nextcloud server version

32.0.3

### Using a reverse proxy?

Yes

### Android logs

_No response_

### Server error logs

```bash

```

### Additional information

_No response_