[Subtask] Add list, alter, and drop support for Semantic Models in relational storage

### Describe the subtask

Add relational persistence for listing, altering, and dropping Semantic Models. This includes the remaining mappers and SQL providers, metadata service and JDBC backend integration, optimistic concurrency, cascading deletion, garbage collection, version retention, and H2/MySQL/PostgreSQL tests.

Alter must append a complete version atomically. Drop and parent cascades must consistently clean up identity and version data.

Managed catalog operations, REST APIs, and clients are out of scope.

### Parent issue

#12209

Start by reading the remaining mappers and SQL providers, then follow the metadata service and JDBC backend integration. Run the H2, MySQL, and PostgreSQL tests while tracing optimistic concurrency, cascading deletion, garbage collection, and version retention. Done means relational listing, atomic complete-version alters, and consistent cleanup on drops and parent cascades.

Written by the indexing model from the issue text.