fix(passbolt): persist GPG keyring as volume to survive restarts

Passbolt's entrypoint creates /var/lib/passbolt/.gnupg/pubring.kbx
as root while PHP-FPM runs as www-data. Without a volume this file
is recreated with wrong ownership on every container recreate, breaking
all GPG operations. Mounting the dir as a volume keeps the chown
33:33 fix permanent.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

passbolt/compose.yml

@@ -24,6 +24,7 @@ services:
     volumes:
       - ../.data/passbolt/gpg:/etc/passbolt/gpg
       - ../.data/passbolt/jwt:/etc/passbolt/jwt
+      - ../.data/passbolt/gnupg:/var/lib/passbolt/.gnupg
     depends_on:
       db:
         condition: service_healthy