feat: task trash, triage trash and retention settings for every area; admin can forbid keeping things for good

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

docker-compose.yml

@@ -18,6 +18,7 @@ services:
       - BASE_URL=${BASE_URL:-http://localhost:8080}
       - ALLOW_REGISTRATION=${ALLOW_REGISTRATION:-false}
       - TRUSTED_PROXIES=${TRUSTED_PROXIES:-private}
+      - RETENTION_ALLOW_NEVER=${RETENTION_ALLOW_NEVER:-}
       - LOGIN_PROTECTION=${LOGIN_PROTECTION:-true}
       - LOG_LEVEL=${LOG_LEVEL:-info}
       - DEBUG=${DEBUG:-false}