Replace the C worker finish callbacks that publish errors, final block sizes,
consumed bytes, and completion signals with a Rust-owned publication path. The
nested projection keeps the job counters and pthread operations private to C,
while Rust preserves the error/success ordering and size_t wrapping behavior.
The consumed-size assertion remains a C validation callback at the original
point before publication.
Test Plan:
- git diff --cached --check
- capped cargo check --tests
- capped cargo clippy --tests -- -A clippy::manual-bits -D warnings
- capped make -j1
- capped make -j1 -C tests test
- standalone hybrid cargo test remains unavailable because its link lacks the
pre-existing ZSTD_rust_dctx_trace_view, ZSTD_rust_dctx_view, and
ZSTD_rust_block_context_init symbols