enhance(LargeSmtForest tests): expand LargeSmtForest property test coverage

[AlexWaker]

This PR expands the property-based test coverage for LargeSmtForest.

Previously, the forest-level property tests were mostly limited to entries(). This change adds a broader set of reference-model-driven property tests covering core query, mutation, metadata, constructor, and truncation behavior.

The new tests now exercise:

• query consistency for get(), entries(), and entry_count()
• selected open() consistency checks against a reference Smt
• metadata consistency for latest_version(), latest_root(), lineage_roots(), roots(), and root_info()
• mutation behavior for add_lineage(), update_tree(), and update_forest()
• failure semantics, including duplicate lineages, bad version transitions, and invalid forest batches
• constructor behavior when initializing a forest from a pre-populated backend
• retention and visibility semantics for with_config() and truncate()

In addition, the property test helpers and generators were refactored to make the coverage easier to extend and maintain.

Closes #879.