Adds a flag-combinations table for bw test (selectors + the
HIJKMSp/IJKMp default-flag split), bw metadata -k/-b/-f (with
the -f sensitive-data warning), bw items --blame/-f, bw verify
-o bundle:, bw hash -m/-d. Also documents the shared target-
selector grammar.
Surfaced by the left4me-integration session, where the agent
relied on bare bw test / bw metadata / bw items invocations and
missed leverage from the available flags.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>