Persist login sessions, seed default users, and let editors skip the paszin

- compose: keep DataProtection keys in a named volume so redeploying no
  longer logs everybody out
- seed default family members at startup (init.sql only runs on a fresh
  MySQL volume, existing databases never got new members like Mattis)
- editors no longer need the paszin to submit an article or edit their
  own article; the editor session now survives submitting/editing
  (previously the paszin flow replaced or signed out the editor cookie)

compose.yml

@@ -26,6 +26,10 @@ services:
       # Archief-edities: bestaande PDF's tonen én pas gedrukte kranten
       # worden hier bewaard (resources/archive)
       - ./resources/archive:/app/archive
+      # DataProtection-sleutels (versleuteling van login-cookies en
+      # antiforgery-tokens). Zonder dit volume worden alle sessies
+      # ongeldig bij elke herdeploy van de app-container.
+      - app-dataprotection:/root/.aspnet/DataProtection-Keys
     depends_on:
       mysql:
         condition: service_healthy
@@ -53,3 +57,4 @@ services:
 
 volumes:
   mysql-data:
+  app-dataprotection: