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/lib/answers/-params-pull-and-merge.sh

@@ -0,0 +1,17 @@
+#!/bin/bash
+
+_copier_answers_params_pull_and_merge() {
+  [ -f "${HL_V1_COPIER_PARAMS_FILE}" ] || return 0
+  [ -f "${HL_V1_COPIER_FILE_COPIER_ANSWERS_NEW}" ] || return 0
+
+  if command -v yq >/dev/null 2>&1; then
+    local TMP_WORK_FILE="tmp-work-file.yml"
+    yq eval-all '. as $item ireduce ({}; . * $item)' \
+      "${HL_V1_COPIER_FILE_COPIER_ANSWERS_NEW}" \
+      "${HL_V1_COPIER_PARAMS_FILE}" >"${TMP_WORK_FILE}"
+    mv "${TMP_WORK_FILE}" "${HL_V1_COPIER_FILE_COPIER_ANSWERS_NEW}"
+  else
+    # Fallback: params file wins as full override when yq is unavailable.
+    cp "${HL_V1_COPIER_PARAMS_FILE}" "${HL_V1_COPIER_FILE_COPIER_ANSWERS_NEW}"
+  fi
+}