chore: rename remaining subfeed references to siftlode

Replace the leftover 'subfeed' name across logger names + log_config,
frontend localStorage keys, Postgres user/db/volume defaults in the
compose files, .env.example, config.py, backup/restore scripts and the
README. Pure rename; no behavioural change. localStorage keys move from
subfeed.* to siftlode.* (one-time UI-state reset is acceptable).

scripts/restore.sh

@@ -5,7 +5,7 @@ set -e
 FILE="$1"
 if [ -z "$FILE" ]; then echo "Usage: restore.sh <dumpfile>"; exit 1; fi
 if [ ! -f "$FILE" ]; then echo "Dump file not found: $FILE"; exit 1; fi
-USER_NAME="${POSTGRES_USER:-subfeed}"
-DB_NAME="${POSTGRES_DB:-subfeed}"
+USER_NAME="${POSTGRES_USER:-siftlode}"
+DB_NAME="${POSTGRES_DB:-siftlode}"
 docker compose exec -T db pg_restore -U "$USER_NAME" -d "$DB_NAME" --clean --if-exists < "$FILE"
 echo "Restored $FILE"