Install argon2 to hash the admin token

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tasks/main.yml

@@ -6,6 +6,8 @@
     install_recommends: yes
     pkg:
       - "sqlite3"
+      # hash an admin token: echo -n "$TOKEN" | argon2 "$(openssl rand -base64 32)" -e -id -k 65540 -t 3 -p 4
+      - "argon2"
 
 - name: setup vaultwarden directories
   file: