Reuse genesis page data for continuation global proof

[MauroToscano]

Summary

• Reuse genesis page data computed from the initial carried memory image when proving the continuation global memory proof.
• Split global memory config construction so the prover can use precomputed page data while the verifier still rebuilds from ELF + private_inputs.

Rationale

prove_continuation already builds the initial paged image before epochs start. The global proof only needs genesis page data for touched pages, so rebuilding the dense genesis image from ELF + private_inputs inside prove_global is redundant.

The verifier path is intentionally unchanged: it still rebuilds configs from the ELF and private input carried in the bundle so genesis remains independently checked.

Verification

• cargo fmt --all
• make compile-programs-asm CLANG=/opt/homebrew/opt/llvm/bin/clang
• cargo test -p lambda-vm-prover continuation -- --nocapture
• cargo test -p lambda-vm-prover local_to_global -- --nocapture
• make lint