DatabaseException - "unable to open database file" on iOS

**Package**: [flutter_cache_manager]
**Platform**: iOS
**Error**: `DatabaseException(Error Domain=SqfliteDarwinDatabase Code=14 "unable to open database file")`

---

### 🔍 Description

While using the package, I occasionally encounter the following error on iOS:
```
#0 wrapDatabaseException (package:sqflite_platform_interface/src/platform_exception.dart:12)

#1 SqfliteDatabaseMixinExt._txnRawUpdateOrDelete. (package:sqflite_common/src/database_mixin.dart:318)

#2 BasicLock.synchronized (package:synchronized/src/basic_lock.dart:36)

#3 SqfliteDatabaseMixin.txnSynchronized (package:sqflite_common/src/database_mixin.dart:517)

```

This seems to happen when the cache manager tries to update or insert entries in the database. It appears that the database file is either not found or not accessible at runtime.

---

### ✅ What I’ve Tried

- Verified that I'm not deleting or moving the database file manually.
- Tried using `CacheManager` with a custom config and custom database name.
- Happens mostly in production or TestFlight builds — not consistently reproducible in debug mode.

---

The report names no repository file or test; start by reproducing the failure on iOS or a TestFlight build and trace the cache manager's database update and insert paths. Compare the custom and default database configurations, then document the cause and verify that the affected cache operations complete without the database-open error.

Written by the indexing model from the issue text.