[Utility][Persistence][Savepoints/Rollbacks] Implement change tracking in `UtilityUnitOfWork` to allow ephemeral state and remove side effects

[deblasis]

Objective

Extend the UtilityUnitOfWork logic so that it transparently works like an ephemeral "WorldState" that becomes valid/persisted only when it's committed successfully. Until then, all changes are tracked, and applied in memory but NOT persisted.

Origin Document

562

Goals

• Obtain a PersistenceReadContext
• Implement PersistenceWriteContext but track changes in memory instead of targeting the datastores
• Implement Commit logic that flushes the changes correctly to the real Persistence layer

Deliverable

• [ ] A PR with implementation tending to the goals above
• [ ] Deterministic unit tests to verify the logic above

Non-goals / Non-deliverables

• Implement a simple Rollback that throws away all the ephemeral state (tracked in #435)

General issue deliverables

• [ ] Update the appropriate CHANGELOG(s)
• [ ] Update any relevant local/global README(s)
• [ ] Update relevant source code tree explanations
• [ ] Add or update any relevant or supporting mermaid diagrams

Testing Methodology

• [ ] Task specific tests or benchmarks: make ...
• [ ] New tests or benchmarks: make ...
• [ ] All tests: make test_all
• [ ] LocalNet: verify a LocalNet is still functioning correctly by following the instructions at docs/development/README.md

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Creator: @deblasis Co-Owners: @Olshansk

[Olshansk]

The goals make sense to me. Looking forward to seeing the design & implementation around the tree structures for this!