PDF download/open fails (stuck at error) since 33.1.1, works fine in 33.1.0

### ⚠️ 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

Description :
Downloading or opening PDF files fails consistently, both via explicit download and via tapping to preview/open. Images work fine (download and preview). The bug appeared starting with version 33.1.1 and is still present in 34.0.0.
Steps to reproduce :
Open any PDF file in the app (or tap "Download")
Download reaches 100% then fails with an error
Same PDF works fine when downloaded via the web browser interface

Environment :
Nextcloud Android app: tested on 33.1.1 and 34.0.0 (both fail), 33.1.0 works correctly
Server version: 33.0.5.1
Server log shows the GET request completing without error (HTTP request reaches the server fine, no exception, no error code) — issue appears to be client-side, after the file is received
Tested both with Play Store and F-Droid builds — same issue on both
Server hosted at Infomaniak
Additional notes :
Filename in test case included accented characters and spaces (e.g. "2025 10 optimisé.pdf"), though images with similar filenames work fine, so this may not be the root cause

### Expected behaviour

PDF should download/open like it did in 33.1.0.
Actual behaviour :
Download/open fails at 100% for PDF files specifically. Images are unaffected.

### Actual behaviour

Download/open fails at 100% for PDF files specifically. Images are unaffected.

### Android version

16

### Device brand and model

Honor 200 pro

### Stock or custom OS?

Stock

### Nextcloud android app version

Nextcloud Android app: tested on 33.1.1 and 34.0.0 (both fail), 33.1.0 works correctly

### Nextcloud server version

Server version: 33.0.5.1

### Using a reverse proxy?

I don't know

### Android logs

_No response_

### Server error logs

```bash

```

### Additional information

_No response_

Reproduce PDF download and preview failures on Android 16 with app versions 33.1.1 and 34.0.0, then compare the same flow with 33.1.0 where it works. Investigate the client-side handling after a PDF reaches 100%, using the unaffected image flow as a comparison; done means PDFs download and open successfully without regressing images.

Written by the indexing model from the issue text.