update docs

docs/render.sh

@@ -0,0 +1,18 @@
+#!/bin/bash
+# Re-render all Graphviz diagrams to SVG.
+# Run after editing any .dot file under docs/graphs/.
+# Usage: ./render.sh
+set -euo pipefail
+
+GRAPHS_DIR="$(cd "$(dirname "$0")/graphs" && pwd)"
+
+if ! command -v dot &>/dev/null; then
+    echo "graphviz not found — install with: sudo apt install graphviz" >&2
+    exit 1
+fi
+
+for f in "$GRAPHS_DIR"/*.dot; do
+    svg="${f%.dot}.svg"
+    echo "==> $(basename "$f") → $(basename "$svg")"
+    dot -Tsvg "$f" -o "$svg"
+done