passwords: Phase B browser/manager propagation engine (pwgen + pwstore + CLI)

Add the secondary-persona path from docs/BROWSER-ROTATION.md: ingest a password
manager / browser store, take a mandatory verified sealed backup, generate fresh
strong passwords, hand the human a ready-to-finish task at the MFA wall, and commit
the new value into the manager only after the site change is confirmed.

- internal/pwgen: crypto/rand generator (rejection sampling, per-class guarantee,
  vault-native — never returns plaintext as a Go string).
- internal/pwstore: Manager/ItemUpdater/BulkImporter contracts, secrets-free
  RedactIdentity, and five adapters — bitwarden (bw, stdin), keepassxc
  (keepassxc-cli, stdin), 1password (op, argv assignment with documented caveat),
  chrome/firefox (tmpfs CSV ingest-and-shred). All real code; validation status is
  data (MOCK-ONLY against fake binaries/CSVs, recorded in the design doc).
- internal/pwstore/stage.go: age-sealed staged-list (WriteStaged/ReadStaged) +
  StagedImporter — the only artifacts crossing the plan->commit gap, never plaintext.
- cmd/incredigo: passwords scan|plan|guide|commit. Backup gate seals + round-trip
  verifies before any commit; guide is interactive verify-before-commit; commit is
  headless over a sealed stage. Browser CSV writes are gated behind --allow-csv.

Hard rules honored: backup-before-commit, verify-before-commit, no plaintext on
disk (browser CSV is the flag-gated tmpfs+shred exception), MFA always a human
handoff. go vet + -race clean; end-to-end verified against a fake bw.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

cmd/incredigo/main.go

@@ -54,7 +54,7 @@ func main() {
 	root.PersistentFlags().StringVar(&flagConfig, "config", "", "policy.yaml path")
 	root.PersistentFlags().StringVar(&flagSealer, "sealer", "age", "backup sealer: age (default, authenticated), hmac (authenticated, openssl-only), or openssl (unauthenticated)")
 
-	root.AddCommand(scanCmd(), migrateCmd(), statusCmd(), exportCmd(), importCmd(), rotateCmd(), worklistCmd(), guideCmd())
+	root.AddCommand(scanCmd(), migrateCmd(), statusCmd(), exportCmd(), importCmd(), rotateCmd(), worklistCmd(), guideCmd(), passwordsCmd())
 
 	if err := root.Execute(); err != nil {
 		fmt.Fprintln(os.Stderr, "incredigo:", err)