refactor(compress): expose sequence statistics leaves from Rust

The C definitions of ZSTD_get1BlockSummary() and ZSTD_resetSeqStore()
only forwarded their arguments to Rust, so they duplicated the ABI boundary
without contributing assertions, private-state adaptation, or C-only policy.
Make Rust provide the existing internal symbols directly and remove only the
corresponding C declarations and forwarding bodies. Keep crate-local aliases
for the current compressor-module imports; they are Rust name aliases and do
not add the former ABI symbols back. No other statistics leaf is included.

Test Plan:
- `ulimit -v 41943040; cc -Ilib -Ilib/common -Ilib/compress -Ilib/decompress -Ilib/dictBuilder -Ilib/legacy -Ilib/deprecated -Ilib/zstd -fsyntax-only lib/compress/zstd_compress.c` -- passed
- `ulimit -v 41943040; cargo +nightly fmt --manifest-path rust/Cargo.toml --all -- --check` -- passed
- `git diff --check` and `git diff --cached --check` -- passed
- No cargo builds, make commands, or tests run, per request

lib/compress/zstd_compress.c

@@ -2137,10 +2137,7 @@ void ZSTD_rust_confirmRepcodesAndEntropyTables(
         ZSTD_compressedBlockState_t** nextCBlock);
 void ZSTD_rust_storeLastLiterals(SeqStore_t* seqStorePtr,
                                  const BYTE* anchor, size_t lastLLSize);
-void ZSTD_rust_resetSeqStore(SeqStore_t* ssPtr);
 void ZSTD_rust_validateSeqStore(const SeqStore_t* seqStore, U32 minMatch);
-BlockSummary ZSTD_rust_get1BlockSummary(const ZSTD_Sequence* seqs,
-                                        size_t nbSeqs);
 U32 ZSTD_rust_resolveRepcodeToRawOffset(const U32 rep[ZSTD_REP_NUM],
                                         U32 offBase, U32 ll0);
 size_t ZSTD_rust_loadCEntropy(ZSTD_compressedBlockState_t* bs, void* workspace,
@@ -5355,11 +5352,6 @@ ZSTD_BlockCompressor_f ZSTD_selectBlockCompressor(ZSTD_strategy strat, ZSTD_Para
     return selectedCompressor;
 }
 
-void ZSTD_resetSeqStore(SeqStore_t* ssPtr)
-{
-    ZSTD_rust_resetSeqStore(ssPtr);
-}
-
 static size_t ZSTD_rust_externalSequenceProducer_transfer(
         void* context, ZSTD_SequencePosition* seqPos,
         const ZSTD_Sequence* inSeqs, size_t inSeqsSize,
@@ -8540,11 +8532,6 @@ ZSTD_compressSequencesAndLiterals(ZSTD_CCtx* cctx,
             litCapacity, decompressedSize);
 }
 
-BlockSummary ZSTD_get1BlockSummary(const ZSTD_Sequence* seqs, size_t nbSeqs)
-{
-    return ZSTD_rust_get1BlockSummary(seqs, nbSeqs);
-}
-
 /*======   Finalize   ======*/
 
 static ZSTD_inBuffer inBuffer_forEndFlush(const ZSTD_CStream* zcs)