Preserve LoadOptions through lossless edits

[jskoiz]

Summary

• Preserve the caller's LoadOptions on LosslessStream instances.
• Use those options for low-level LosslessEdit validation and final replay.
• Add focused regressions for no-op, scalar, and structural edits.

Verification

• Local: cargo fmt --all --check
• Local: git diff --check
• Local: cargo test --locked --test lossless_roundtrip (50 passed)
• Local: cargo test --locked (all unit, integration, and 8 doctests passed)
• Local: cargo clippy --locked --all-targets -- -D warnings
• Local: scripts/check-feature-clippy.sh
• Hosted CI/merge state: not yet observed; this is a draft PR and has not been merged.

Notes/Risks

• The change is limited to lossless edit option propagation and regression coverage.
• No public option schema or compatibility fallback was added.

Closes #75