Add markdown aggregation script and generated aggregated.md

aggregate.sh

@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+# Aggregate all dossier markdown into a single aggregated.md at repo root.
+# Order: pages/*.md (index.md first, then page-NN.md numerically), then dossier.md.
+set -euo pipefail
+cd "$(dirname "$0")"
+
+out=aggregated.md
+: > "$out"
+
+emit() {
+  printf '\n\n<!-- ===== source: %s ===== -->\n\n' "$1" >> "$out"
+  cat "$1" >> "$out"
+}
+
+# sort -V: 'index.md' sorts before 'page-*', page numbers sort naturally (robust to 3-digit pages)
+while IFS= read -r f; do emit "$f"; done < <(ls pages/*.md | sort -V)
+emit dossier.md
+
+echo "Wrote $out — $(grep -c 'source:' "$out") sources, $(wc -l < "$out") lines"