0da789cd96
Migration 0002 added fsid column with DEFAULT 0 but never populated existing rows. Now PopulateLegacyFSIDs() runs after 0002 to extract fsid from legacy options string or generate random. Also: move generateRandomFSID to internal/system to avoid import cycles. Migration 0004 drops the legacy options column. Version: 0.3.1 -> 0.3.2