feat(compress): move CCtx block-state copy into Rust

Pass the destination compressed-block-state pointer slot and source state
through the copyCCtx bridge, then perform the final copy in Rust after reset
has established the destination. Remove the redundant C memcpy callback while
preserving private callback ordering and early-error behavior.

Add focused tests for copied repcodes and entropy repeat state.

Test Plan:
- ulimit -v 41943040 && CARGO_BUILD_JOBS=1 cargo test --manifest-path rust/Cargo.toml
- ulimit -v 41943040 && CARGO_BUILD_JOBS=1 cargo clippy --manifest-path rust/Cargo.toml --all-targets -- -D warnings
- ulimit -v 41943040 && make -j1
- ulimit -v 41943040 && make -j1 -C tests test-zstream ZSTREAM_TESTTIME=-T2s
- ulimit -v 41943040 && make -j1 -C tests test-fuzzer FUZZERTEST=-T3s FUZZER_FLAGS=--no-big-tests
- ulimit -v 41943040 && cargo fmt --manifest-path rust/Cargo.toml -- --check
- git diff --check

lib/compress/zstd_compress.c

@@ -481,7 +481,8 @@ typedef struct {
     ZSTD_rust_copyCCtxMarkTables_f markTablesClean;
     ZSTD_rust_copyCCtxCopyState_f copyMatchState;
     ZSTD_rust_copyCCtxCopyState_f copyDictState;
-    ZSTD_rust_copyCCtxCopyState_f copyBlockState;
+    ZSTD_compressedBlockState_t** destinationBlockState;
+    const ZSTD_compressedBlockState_t* sourceBlockState;
     int zbuff;
 } ZSTD_rust_copyCCtxInternalState;
 size_t ZSTD_rust_copyCCtxInternal(
@@ -522,7 +523,7 @@ typedef char ZSTD_rust_copy_cctx_internal_state_layout[
                 == 3 * sizeof(void*) + sizeof(U64)
          && offsetof(ZSTD_rust_copyCCtxInternalState, zbuff)
                 == 3 * sizeof(void*) + sizeof(U64)
-                 + 9 * sizeof(void*)
+                 + 10 * sizeof(void*)
          && sizeof(ZSTD_rust_copyCCtxInternalState)
                 == ((offsetof(ZSTD_rust_copyCCtxInternalState, zbuff)
                      + sizeof(int) + sizeof(void*) - 1) / sizeof(void*))
@@ -4854,16 +4855,6 @@ static void ZSTD_rust_copyCCtx_copy_dict_state(
     dst->dictContentSize = src->dictContentSize;
 }
 
-static void ZSTD_rust_copyCCtx_copy_block_state(
-        void* context, const void* srcCCtx)
-{
-    ZSTD_CCtx* const dst = (ZSTD_CCtx*)context;
-    const ZSTD_CCtx* const src = (const ZSTD_CCtx*)srcCCtx;
-    ZSTD_memcpy(dst->blockState.prevCBlock,
-                src->blockState.prevCBlock,
-                sizeof(*src->blockState.prevCBlock));
-}
-
 static size_t ZSTD_rust_copyCCtx_internal_callback(
         void* context, const void* srcCCtx,
         const ZSTD_frameParameters* fParams,
@@ -4882,7 +4873,8 @@ static size_t ZSTD_rust_copyCCtx_internal_callback(
     state.markTablesClean = ZSTD_rust_copyCCtx_mark_tables_clean;
     state.copyMatchState = ZSTD_rust_copyCCtx_copy_match_state;
     state.copyDictState = ZSTD_rust_copyCCtx_copy_dict_state;
-    state.copyBlockState = ZSTD_rust_copyCCtx_copy_block_state;
+    state.destinationBlockState = &((ZSTD_CCtx*)context)->blockState.prevCBlock;
+    state.sourceBlockState = ((const ZSTD_CCtx*)srcCCtx)->blockState.prevCBlock;
     state.zbuff = zbuff;
     return ZSTD_rust_copyCCtxInternal(&state);
 }