EXP-0155A: expose public instance projections

[buger]

Summary

• expose the existing immutable live and replayed instance projections through StateMachineExecutionEngine
• export the engine value and projection types through the public SDK
• add isolated public-surface and TypeScript-AST oracles without changing the frozen legacy fixture

Boundaries

• stacked on EXP-0153 commit 155d7e675be1773847a9a7a34d1d16502876b6f0
• exactly three paths; product +31/-0 physical lines
• no new projection, selector, hash, copy, wire, store, or authority

Validation

• candidate Prettier and ESLint passed
• new focused Jest: 3/3 passed
• frozen EXP-0147 Jest: 10/10 passed
• TypeScript retained exactly the four pinned baseline diagnostics
• isolated SDK ESM, CJS, and NodeNext type consumers passed