Fixes for problems reported on GitHub.

Large files no longer crash or freeze. Encrypt and Decrypt now stream files straight to and from disk instead of holding them in memory, so a multi-megabyte file works the same as a small one. This covers the Encrypt and Decrypt tabs, files opened or shared into PGPony, and the Quick Action share sheet.

Other apps can decrypt again. Release builds were renaming part of the OpenPGP API, which crashed every mail app that asked PGPony to decrypt (FairEmail, K-9, Thunderbird).

The passphrase prompt no longer opens already saying the passphrase was wrong, and entering it once is now enough — apps used to need a second Unlock press before showing the message.

Importing a file with several keys in it now imports all of them. Before, only the first was imported and PGPony still reported success.

OpenPGP cards with KDF enabled (kdf-setup) now work. Their PIN is hashed as the card expects instead of being sent as plain text.

Decrypting no longer blocks the interface while it works, which was causing freezes on some devices.
