template-engine-copier skill: initial import

Copier + Jinja template-repository design skill: reference architecture,
implementation workflow, validation checklist, and a full worked example
template (questionnaire, extensions, resolvers, wrapper-first .scripts).

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

example/.scripts/copier/api/bootstrap-one.sh

@@ -0,0 +1,7 @@
+#!/bin/bash
+
+set -e
+
+. ./.scripts/copier/lib/--index.sh "$@"
+
+_copier_bootstrap_one