Remove debug eprintln logs from Rust decoder

[tamashi095]

The direct.rs and extract.rs modules have leftover debug logging ([debug] ObjectSet:, [debug] obj_change) that prints to stderr on every checkpoint. These were added during development and should be removed.

Files:

• native/rust-decoder/src/direct.rs — ObjectSet size and obj_change type lookups
• native/rust-decoder/src/extract.rs — ObjectSet decode stats