Add jfr-demo: JFR + Mission Control profiling of a live Spring Boot app

Custom OrderProcessed event, CPU/allocation/lock workloads, a diagnostic
endpoint over the JVM's live FlightRecorder state, a JUnit test using the
jdk.jfr.Recording API, and nine captured recordings (flagship, mid-flight
snapshot, isolated vs concurrent threshold comparisons, and a real
dump+stop duplication bug) with their docs/output/*.txt transcripts.

scripts/load.sh

@@ -0,0 +1,39 @@
+#!/usr/bin/env bash
+# Generates the same real load used to produce docs/output/*.txt against a
+# running instance of the app (localhost:8080 by default).
+#
+# Usage: scripts/load.sh {cpu|alloc|lock|orders|all}
+set -euo pipefail
+HOST="${HOST:-localhost:8080}"
+
+cpu() {
+  echo "6 concurrent fibonacci(38) calls..."
+  for i in 1 2 3 4 5 6; do curl -s "$HOST/api/cpu/fibonacci?n=38" -o /dev/null & done
+  wait
+}
+
+alloc() {
+  echo "3 concurrent allocation-churn calls..."
+  for i in 1 2 3; do curl -s "$HOST/api/alloc/churn?iterations=400000" -o /dev/null & done
+  wait
+}
+
+lock() {
+  echo "one 16-worker, 20ms-hold lock-contention burst..."
+  curl -s "$HOST/api/lock/contend?workers=16&holdMillis=20"; echo
+}
+
+orders() {
+  echo "60 order-processing calls (custom JFR event)..."
+  for i in $(seq 1 60); do curl -s "$HOST/api/orders/process?items=$((3 + i % 5))" -o /dev/null; done
+  echo "done"
+}
+
+case "${1:-all}" in
+  cpu) cpu ;;
+  alloc) alloc ;;
+  lock) lock ;;
+  orders) orders ;;
+  all) cpu; alloc; lock; orders ;;
+  *) echo "usage: $0 {cpu|alloc|lock|orders|all}" >&2; exit 1 ;;
+esac