feat(compress): move sequence-store validation to Rust

Keep the C DEBUGLEVEL gate and delegate the read-only match-length validation through the existing SeqStore ABI. Preserve long-match side-band decoding and the original 3-or-4 byte lower-bound assertion.

Test Plan:

- cargo test --manifest-path rust/Cargo.toml --no-default-features --features compression

- cargo clippy --manifest-path rust/Cargo.toml --no-default-features --features compression --all-targets

- cargo +nightly fmt --manifest-path rust/Cargo.toml

- make -B -C lib -j2 lib

- make -C tests -j2 fuzzer

- tests/fuzzer -s4560 -t47 -i48 -v

lib/compress/zstd_compress.c

@@ -277,6 +277,7 @@ void ZSTD_rust_storeLastLiterals(SeqStore_t* seqStorePtr,
 void ZSTD_rust_resetSeqStore(SeqStore_t* ssPtr);
 size_t ZSTD_rust_fastSequenceLengthSum(const ZSTD_Sequence* seqBuf,
                                        size_t seqBufSize);
+void ZSTD_rust_validateSeqStore(const SeqStore_t* seqStore, U32 minMatch);
 size_t ZSTD_rust_convertSequencesNoRepcodes(
         SeqDef* dstSeqs, const ZSTD_Sequence* inSeqs, size_t nbSequences);
 BlockSummary ZSTD_rust_get1BlockSummary(const ZSTD_Sequence* seqs,
@@ -2348,15 +2349,7 @@ static size_t ZSTD_fastSequenceLengthSum(ZSTD_Sequence const* seqBuf, size_t seq
 static void ZSTD_validateSeqStore(const SeqStore_t* seqStore, const ZSTD_compressionParameters* cParams)
 {
 #if DEBUGLEVEL >= 1
-    const SeqDef* seq = seqStore->sequencesStart;
-    const SeqDef* const seqEnd = seqStore->sequences;
-    size_t const matchLenLowerBound = cParams->minMatch == 3 ? 3 : 4;
-    for (; seq < seqEnd; ++seq) {
-        const ZSTD_SequenceLength seqLength = ZSTD_getSequenceLength(seqStore, seq);
-        assert(seqLength.matchLength >= matchLenLowerBound);
-        (void)seqLength;
-        (void)matchLenLowerBound;
-    }
+    ZSTD_rust_validateSeqStore(seqStore, (U32)cParams->minMatch);
 #else
     (void)seqStore;
     (void)cParams;