Complete TUI coverage and security audit

README.md

@@ -41,6 +41,8 @@ documented in [`docs/otp.md`](docs/otp.md).
 The complete command matrix, shell completion interface, deliberate no-process
 differences, and executable security audit are documented in
 [`docs/cli-parity.md`](docs/cli-parity.md).
+The Mutt-inspired terminal interaction model, default keys, and complete TUI
+operation matrix are documented in [`apps/tui/COMMANDS.md`](apps/tui/COMMANDS.md).
 Lossless structured entry fields, semantic/sensitivity metadata, conflict
 tokens, and atomic frontend saves are documented in
 [`docs/entry-documents.md`](docs/entry-documents.md).