fix: wait for safeStorage availability before encrypt/decrypt

[edospadoni]

Problem

On Windows, the app sometimes fails to auto-login at startup. This happens because safeStorage (which uses DPAPI on Windows) may not be immediately available when the system boots.

The previous code called safeStorage.encryptString() and safeStorage.decryptString() without checking if encryption was available, causing silent failures.

Solution

Added waitForSafeStorage() helper method that:

• Checks safeStorage.isEncryptionAvailable() before any encrypt/decrypt operation
• Retries up to 20 times with 500ms intervals (max 10 seconds wait)
• Logs each retry attempt for debugging

Applied this check to:

• autoLogin(): waits for safeStorage before decrypting saved credentials
• saveLoggedAccount(): waits for safeStorage before encrypting credentials to save

[github-actions]

Automatic builds from https://github.com/NethServer/nethlink/actions/runs/20989012190.
Commit: 84ac349

Name	Platform	Link
win-app.exe	Windows (x64)	Link
macos-app-x64.dmg	MacOS (x64)	Link
macos-app-arm64.dmg	MacOS (arm64)	Link
linux-app.AppImage	Linux (x64)	Link

[github-actions]

Automatic builds from https://github.com/NethServer/nethlink/actions/runs/20990257900.
Commit: 6539ec2

Name	Platform	Link
win-app.exe	Windows (x64)	Link
macos-app-x64.dmg	MacOS (x64)	Link
macos-app-arm64.dmg	MacOS (arm64)	Link
linux-app.AppImage	Linux (x64)	Link

[github-actions]

Automatic builds from https://github.com/NethServer/nethlink/actions/runs/20990915929.
Commit: ab31bf9

Name	Platform	Link
win-app.exe	Windows (x64)	Link
macos-app-x64.dmg	MacOS (x64)	Link
macos-app-arm64.dmg	MacOS (arm64)	Link
linux-app.AppImage	Linux (x64)	Link