iOS - "Kommunikation mit der Hilfs-App nicht möglich" - no communication with helper app

### Summary

Can connect to a vault on Google Drive and browse, but not download/open files in iPhone files app

### Please agree to the following

- [x] I have searched [existing issues](https://github.com/cryptomator/ios/issues?q=) for duplicates
- [x] I agree to follow this project's [Code of Conduct](https://github.com/cryptomator/ios/blob/develop/.github/CODE_OF_CONDUCT.md)

### System Setup

- iOS: 26.5
- Cryptomator: 3.01

### Cloud Type

_No response_

### Steps to Reproduce

I have recently set up a new vault after having used the (very old) app with a (very old) vault. This is a brand new vault and not a vault converted from an earlier vault format. The vault was setup on Linux is lives on a personal Google Drive.

Steps to reproduce:

- Connect to vault on Google Drive and enter password
- Open files app -> Cryptomator -> go into vault
- Browse vault directory structure (works)
- Click on any file (or the download button) -> error message

### Expected Behavior

Ability to not only browse vault structure but being able to open or download files from vault in iOS vault app.

### Actual Behavior

What works:

- I can add the vault in Cryptomator on iOS and Cryptomator verifies the password (or rejects if I enter a wrong password)
- I can browse the vault in the iOS files app and see folders and file names

What doesn't work:
If I try to open or download a file in the iOS files app, I get an error message information me that "Kommunikation mit der Hilfs-App nicht möglich" (no comms with helper app possible).

Unsuccessful attempts to fix:
- I initially had the preview app installed but also tried removing that, but that didn't change anything.
- I have also in the mean time restarted the phone, removed and re-added Cryptomator as a file source in the files app and disconnected and reconnected to the vault in the Cryptomator app. No success.

### Reproducibility

Always

### Relevant Log Output

```shell
Log data:
ios.fileprovider:

2026/05/15 07:08:52:414 enumerateItems getAdapter failed with: defaultLock for identifier: NSFileProviderItemIdentifier(_rawValue: NSFileProviderRootContainerItemIdentifier)
2026/05/15 07:08:52:417 enumerateItems getAdapter failed with: defaultLock for identifier: NSFileProviderItemIdentifier(_rawValue: BF0AA7B9-3265-4031-A670-C168C27E6BAA:6)
2026/05/15 07:08:52:421 enumerateItems getAdapter failed with: defaultLock for identifier: NSFileProviderItemIdentifier(_rawValue: BF0AA7B9-3265-4031-A670-C168C27E6BAA:7)

ios:
2026/05/15 07:12:06:857 Vault BF0AA7B9-3265-4031-A670-C168C27E6BAA unlock status: Unlocked
2026/05/15 07:12:07:126 Setting trialExpirationDate was removed
2026/05/15 07:12:07:127 Setting fullVersionUnlocked was written with value true
2026/05/15 07:12:07:127 Setting hasRunningSubscription was written with value false
```

### Anything else?

_No response_