feat: golang-cli v1.0.0 — generic command-tree CLI library

Reusable, generics-based CLI extracted from vpp-evpn's cmd/evpnc:
a declarative command tree (Node[C]) from which dispatch, '?'-help and
TAB-completion are derived, an interactive Shell[C], dynamic slot
resolvers (context-dependent via captured args), text-or-JSON output
(Emit), and color helpers (Paint/Label/KV). Builds on Linux and OpenBSD
(readline termios override). Includes a self-contained example and a
design proposal under docs/.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

term_default.go

@@ -0,0 +1,13 @@
+// SPDX-FileCopyrightText: (C) Copyright 2026 Pim van Pelt <pim@ipng.ch>
+// SPDX-License-Identifier: Apache-2.0
+
+//go:build !openbsd
+
+package cli
+
+import "github.com/chzyer/readline"
+
+// applyTermFuncs is a no-op on every platform except OpenBSD, where readline's
+// native termios handling is broken and needs an override (see term_openbsd.go).
+// Elsewhere readline's defaults work as-is.
+func applyTermFuncs(_ *readline.Config) {}