@hackage shikumi-compile0.2.0.3

The compiler layer for shikumi: pure Program -> Program transformations that bake a prompting strategy into a program's per-node parameters or structure (zero-shot, few-shot, chain-of-thought, retrieval-augmented), the owned type CompiledProgram (MasterPlan integration point #6), a minimal Retriever interface with a trivial in-memory implementation, and parameter-state serialization mirroring DSPy's dump_state/load_state. A compiler never calls the LM to try variations and keep the best — that is the optimizer (EP-10). Every acceptance assertion is about the prompt the model would have seen, observed offline through a capturing stub, so the whole package tests with no network.