Add security-7-migration module: Spring Security 6.5.11 vs 7.1.2 jar diff, compile checks and runtime probes

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01YPgGH6aMbSLANL3E2HHmS6

security-7-migration/scripts/compile-old-apis.sh

@@ -0,0 +1,18 @@
+#!/usr/bin/env bash
+# Compiles src/compat/*.java against Security 6.5.11 and 7.1.2 and records javac's answer in output/.
+set -u
+cd "$(dirname "$0")/.."
+mkdir -p target output
+for pair in "security6:6.5.11" "security7:7.1.2"; do
+  profile=${pair%%:*}; v=${pair##*:}
+  mvn -q -B dependency:build-classpath -P$profile -Dmdep.outputFile=target/cp-$v.txt >/dev/null || { echo "classpath failed for $v"; exit 1; }
+  for f in OldSecurity NewSecurity NewManager; do
+    out=output/$( [ $f = OldSecurity ] && echo 05-old-apis || { [ $f = NewSecurity ] && echo 06-fixed-apis || echo 07-new-manager; } )-$v.txt
+    rm -rf target/classes-$f-$v; mkdir -p target/classes-$f-$v
+    {
+      echo "Spring Security $v, compiling $f.java"
+      javac -Xlint:deprecation -proc:none -d target/classes-$f-$v -cp "$(cat target/cp-$v.txt)" src/compat/$f.java 2>&1 | grep -v "^Picked up"
+      echo "javac exit status: ${PIPESTATUS[0]}"
+    } > $out
+  done
+done