Add inheritance module: SINGLE_TABLE vs JOINED vs TABLE_PER_CLASS on Hibernate 7.4.13.Final

Same payment hierarchy mapped three ways plus @MappedSuperclass, run with plain Hibernate on H2.
Tests assert and write the generated DDL, the INSERT/SELECT SQL, row/insert/FK/nullability counts and
the three failures (NOT NULL on a SINGLE_TABLE subclass column, IDENTITY with TABLE_PER_CLASS, querying a
@MappedSuperclass); Bench writes indicative polymorphic-query timings. No docs folder: depth lives in the post.

inheritance/scripts/bench.sh

@@ -0,0 +1,7 @@
+#!/usr/bin/env bash
+# Writes output/04-polymorphic-timings.txt. Timings are indicative: they drift between runs and machines.
+set -euo pipefail
+cd "$(dirname "$0")/.."
+mvn -B -q test-compile dependency:build-classpath -Dmdep.outputFile=target/cp.txt -Dmdep.includeScope=test
+java -cp "target/classes:target/test-classes:$(cat target/cp.txt)" com.ankurm.inheritance.Bench
+cat output/04-polymorphic-timings.txt

inheritance/scripts/run-all.sh

@@ -0,0 +1,9 @@
+#!/usr/bin/env bash
+# Regenerates every file under output/. Needs JDK 25 and Maven 3.9 with access to Maven Central.
+#   01-ddl-*, 02-sql-*, 03-contracts : the JUnit tests (they assert the numbers they print)
+#   04-polymorphic-timings           : scripts/bench.sh (indicative timings, not asserted)
+set -euo pipefail
+cd "$(dirname "$0")/.."
+mvn -B clean test
+./scripts/bench.sh
+ls -1 output