Move stage validation, dictionary clearing, and local/CDict/prefix assignment
selection for the three CCtx dictionary APIs into Rust. Keep the private CCtx
layouts, allocator and by-copy lifetime behavior, CDict ownership, reset
policy, and dictionary-content loader behind explicit C callbacks so the
language boundary carries policy rather than private state.
Test Plan:
- Rust library all-target tests: 517 passed.
- Rust legacy feature matrix: 572 passed.
- Rust and CLI clippy, nightly fmt, native CLI tests (41), and library smoke.
- Native test-zstd, bounded fuzzer (319), zstream (152 + 297), and decode
corpus (1,647) all passed.
- All heavy checks ran serially with CARGO_BUILD_JOBS=1 or make -j1 and
ulimit -v 41943040 (40 GiB virtual memory).
- Commit is intentionally unsigned because configured GPG pinentry was
unavailable and hung during the signing attempt.
ddidderr
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