test(cli): drive migrate audit-metadata-bodies in the --json stdout-purity family

`os migrate audit-metadata-bodies` calls `bootSchemaStack(` and declares
`--json`, so the purity suite's source discovery already counts it, but
FAMILY did not list it and the nightly reconciliation case went red on
main. List it with its bare argv: the dry run is the command's default, so
the drive boots, reads sys_audit_log / sys_activity and writes nothing,
and the three per-member purity assertions now run against it.

Claude-Session: https://claude.ai/code/session_01VvcEokUG1tvVxkceYfR5XB
Co-authored-by: Claude <noreply@anthropic.com>

Author: claude

packages/cli/test/json-stdout-purity.e2e.test.ts

@@ -91,6 +91,12 @@ const FAMILY: Record<string, string[]> = {
   // diagnostic the failed scan produces is emitted before it.
   'migrate account-issuer': [],
   'migrate apply': [],
+  // A dry run is its DEFAULT and the only form driven here: without `--apply`
+  // it boots (plugin-audit's objects registered), reads `sys_audit_log` /
+  // `sys_activity` and writes nothing. Its rewrite runner logs through a sink of
+  // its own, which `--json` points at stderr — a third pollution source beside
+  // the two in the header, so this member is worth driving, not only listing.
+  'migrate audit-metadata-bodies': [],
   'migrate files-to-references': [],
   'migrate meta': ['--stored'],
   'migrate multi-value-columns': [],