feat(netrocks): add SSH private key passphrase prompt

[michaellukashov]

SSH connections using encrypted private keys now prompt the user for a passphrase instead of failing immediately with a generic auth failure.

Changes

New exception type (Erroring.h, Erroring.cpp)

• ProtocolKeyPassphraseNeededError — thrown when libssh reports SSH_ERROR while reading an encrypted key file, distinguishing it from actual credential
  failures.

New IPC message (IPC.h)

• IPC_PI_KEY_PASSPHRASE_NEEDED — communicated from the background broker thread to the main UI thread.

Broker forwarding (HostRemoteBroker.cpp)

• Catches ProtocolKeyPassphraseNeededError and sends the new IPC message, keeping the same pattern as existing auth failure and identity mismatch cases.

Passphrase dialog (InteractiveLogin.cpp, InteractiveLogin.h)

• InteractivePassphraseDialog — password-edit dialog with the same visual style and retry-numbering as the existing auth retry dialog.
• InteractivePassphrase() — public API that shows the dialog and updates the in-memory password on success.

Retry loop (HostRemote.cpp::ReInitialize())

• On IPC_PI_KEY_PASSPHRASE_NEEDED, prompts the user up to 3 attempts.
• On successful entry, retries the connection with the provided passphrase.
• On exhaustion, falls through to OnBroken() with a generic ProtocolError.
• Also gates _login_mode on !_password.empty() so the cached passphrase can be reused on subsequent reinitializations.

Localization (eng.lng, rus.lng, bel.lng)

• 5 new strings: title, retry title, label text, retry label text, and the passphrase prompt.