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/output/01-ddl-table-per-class.txt

@@ -0,0 +1,40 @@
+-- DDL generated by Hibernate 7.4.13.Final for H2, strategy TABLE_PER_CLASS
+-- tables created: 4
+
+
+    create sequence tp_order_seq start with 1 increment by 50;
+
+    create sequence tp_payment_seq start with 1 increment by 50;
+
+    create table tp_bank_transfer_payment (
+        amount numeric(12,2) not null,
+        currency varchar(3) not null,
+        id bigint not null,
+        bank_code varchar(11),
+        iban varchar(34) not null,
+        primary key (id)
+    );
+
+    create table tp_card_payment (
+        amount numeric(12,2) not null,
+        card_last4 varchar(4) not null,
+        currency varchar(3) not null,
+        id bigint not null,
+        network varchar(16),
+        primary key (id)
+    );
+
+    create table tp_order (
+        id bigint not null,
+        payment_id bigint not null,
+        reference varchar(20) not null,
+        primary key (id)
+    );
+
+    create table tp_wallet_payment (
+        amount numeric(12,2) not null,
+        currency varchar(3) not null,
+        id bigint not null,
+        provider varchar(24) not null,
+        primary key (id)
+    );