fix: report scheduled backup failures

infra/postgres-backup.sh

@@ -7,12 +7,14 @@ backup_dir="$HOME/backups/postgres"
 backup="$backup_dir/postgres-latest.sql"
 temporary="$backup.tmp.$$"
 
+log() { logger -t miem-postgres-backup -- "$*" 2>/dev/null || true; }
+
 mkdir -p "$backup_dir"
-trap 'rm -f -- "$temporary"' EXIT HUP INT TERM
+trap 'status=$?; rm -f -- "$temporary"; [ "$status" -eq 0 ] || log "backup failed"; exit "$status"' EXIT HUP INT TERM
 cd "$app_dir"
 
 docker compose exec -T postgres sh -c 'pg_dumpall -U "$POSTGRES_USER"' > "$temporary"
 test -s "$temporary"
 mv "$temporary" "$backup"
 find "$HOME/backups/miem_workers" -maxdepth 1 -type f -name 'miem_workers-*.sql' -delete 2>/dev/null || true
-printf '%s\n' "Created $backup"
+log "created $backup"