feat(core,cli,gui): support two-password accounts without storing the mailbox password

A two-password account signed in with its login password as the mailbox
password, so the key chain never unlocked and the daemon retried forever.

Login now asks for the mailbox password and checks it against the account
(proton-sdk 0.8 `unlock`), so a typo is a retry. The password is never
stored: the keyring blob keeps the per-key passphrases instead, and for a
two-password account only when the user opts in (`--remember`, or the
"Keep unlocked on this computer" switch). By default they live in the
kernel keyring for the login session and the account is locked after a
reboot until `pdfs unlock` or the app supplies them again.

- core: kernelkey module, Error::Locked / WrongMailboxPassword, unlock,
  lock, key_state, ready; blobs written by 3.0.x are migrated on first
  start; token refresh updates only the tokens in the stored blob
- cli: `pdfs unlock [--remember]`, `pdfs lock [--forget]`; status and
  diagnose report the key state; the daemon waits while locked and is
  marked non-dumpable
- gui: mailbox password dialog at sign-in and on open, locked tray state
- po: all catalogs translated
- bump to 3.1.0, depend on proton-sdk and proton-drive-rs 0.8.0

Refs #26.

packaging/PKGBUILD

@@ -9,7 +9,7 @@
 # Build + install:   cd packaging && makepkg -fi
 
 pkgname=proton-drive-linux
-pkgver=3.0.0
+pkgver=3.1.0
 pkgrel=1
 pkgdesc="Unofficial Proton Drive client for Linux: files-on-demand FUSE mount, CLI, GTK4 app + tray"
 arch=('x86_64')