Existing picture claimed as not existing and thus not uploaded - potential data loss

### ⚠️ 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. Enable auto upload
2. Wait until some pictures are claimed as "file not found"
3. Check whether they really do not exist on the local device

### Expected behaviour

Only claim pictures missing and do not upload pictures if they really do not exist on the local device.

### Actual behaviour

Some pictures or videos are not uploaded because they are allegedly not on the device. However, when checking the local device they exist.
If people rely on the "does not exist" and do not double check every single upload statement, at some point they will delete the picture without it being synced, trusting the client to have uploaded everything which existed.

### Android version

15

### Device brand and model

Pixel 8a

### Stock or custom OS?

Stock

### Nextcloud android app version

3.30.6

### Nextcloud server version

30.0.4

### Using a reverse proxy?

Yes

### Android logs

Nextcloud AIO with the additional community container for caddy proxy.

### Server error logs

```bash

```

### Additional information


As an example, look at the file which ends with 2776.jpg. Taping on the file in the upload list pops up the notification that the file does not exist. Searching for the filename, finds it in the same folder which is configured as "upload from" folder in the nextcloud android client.