Project the end-frame stage, format flags, window log, and XXH64 state into
Rust so the Rust end-of-frame orchestrator computes the checksum and invokes
the existing Rust epilogue serializer directly. Remove the C epilogue and
checksum adapter while preserving callback order, output accounting, stage
transitions, and error precedence.
Test Plan:
- CARGO_BUILD_JOBS=1 cargo test --lib zstd_compress::tests::compress_end -- --nocapture
- CARGO_BUILD_JOBS=1 cargo clippy --all-targets -- -D warnings
- CARGO_BUILD_JOBS=1 cargo test
- CARGO_BUILD_JOBS=1 make -j1
- CARGO_BUILD_JOBS=1 make -j1 -C tests test-zstream ZSTREAM_TESTTIME=-T2s
- CARGO_BUILD_JOBS=1 make -j1 -C tests test-fuzzer FUZZERTEST=-T3s FUZZER_FLAGS=--no-big-tests
All commands were run serially with a 40 GiB virtual-memory cap.