Locked vault contents visible via “Save to Files” when vault should be inaccessible

### Summary

When the Cryptomator vault is locked, it’s still possible to access both folder structure and file contents through the iOS “Save to Files” dialog. Even though the vault appears locked in the Cryptomator app, when you try to save something via “Save to Files” (for example, a screenshot or screen recording), you can not only browse folders but also open and view the actual files stored inside the locked vault.

### Please agree to the following

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

### What software is involved?

Environment:
• Operating System: iOS 26.0 (23A340)
• Device: iPhone 16 Pro Max
• Cryptomator: 2.7.2 (1384)
• File Provider Integration: Enabled

### Volume Type

None

### Steps to Reproduce

1. Lock the vault in Cryptomator.
2. Open any app that supports Save to Files (e.g., Photos, Safari).
3. Choose Save to Files.
4. Navigate to the Cryptomator vault location.
5. You can see folders and even open files inside the locked vault.

### Expected Behavior

When the vault is locked, it should be completely inaccessible from all apps and system dialogs.
No folder structure, filenames, or file contents should be visible until the user unlocks the vault through the Cryptomator app.

### Actual Behavior

Even when the vault is locked in the Cryptomator app, using the “Save to Files” option from another iOS app (like Photos or Safari) still allows browsing the vault’s folder structure and opening the actual files inside.
This means the vault’s content is accessible even though it appears locked.

### Reproducibility

Always

### Relevant Log Output

```shell

```

### Anything else?

_No response_