feat(compress): port MT job-table expansion orchestration

ZSTDMT_expandJobsTable previously kept worker-capacity comparison, old-table
synchronization teardown, replacement allocation, initialization failure cleanup,
and mask updates in C. That left the remaining job-table lifecycle orchestration
outside the Rust storage leaves. Add a narrow Rust ABI that exchanges only
opaque storage and scalar mask state and accepts C callbacks for the private
synchronization lifecycle.

The adapter frees the old table before replacement, reuses the existing Rust
create/free leaves with the caller's custom memory, destroys a partially
initialized replacement before freeing it, and updates jobIDMask only after
successful initialization. C still owns ZSTDMT_CCtx and job descriptors, so
worker-facing fields and platform synchronization stay outside the Rust ABI.

Test Plan:
- `cargo test --manifest-path rust/Cargo.toml --no-default-features --features
  compression zstdmt_compress --lib` -- 38 passed.
- `cargo clippy`, `cargo clippy --benches`, and `cargo clippy --tests` -- passed.
- `cargo +nightly fmt --all -- --check` -- passed.
- `make -B -C lib lib-mt` -- passed.
- `make -B -C tests -j2 fullbench poolTests` -- passed.
- `./poolTests` and `./fullbench -i1 -B1000 ../README.md` -- passed.

lib/compress/zstdmt_compress.c

@@ -163,6 +163,15 @@ ZSTD_frameProgression ZSTDMT_rust_frameProgression(
 ZSTD_frameProgression ZSTDMT_rust_frameProgressionAddJob(
         ZSTD_frameProgression progression, size_t srcSize, size_t consumed,
         size_t produced, size_t flushed);
+typedef int (*ZSTDMT_jobTableInitFn)(void* jobTable, unsigned nbJobs,
+                                     size_t jobSize);
+typedef void (*ZSTDMT_jobTableDestroyFn)(void* jobTable, unsigned nbJobs,
+                                         size_t jobSize);
+size_t ZSTDMT_rust_expandJobsTable(
+        void** jobTablePtr, unsigned* jobIDMaskPtr, unsigned nbWorkers,
+        size_t jobSize, ZSTD_customMem cMem,
+        ZSTDMT_jobTableInitFn initSync,
+        ZSTDMT_jobTableDestroyFn destroySync);
 
 typedef struct ZSTDMT_bufferPool_s {
     ZSTDMT_RustBufferPool* rustPool;
@@ -911,16 +920,14 @@ static ZSTDMT_jobDescription* ZSTDMT_createJobsTable(U32* nbJobsPtr, ZSTD_custom
 }
 
 static size_t ZSTDMT_expandJobsTable (ZSTDMT_CCtx* mtctx, U32 nbWorkers) {
-    U32 nbJobs = nbWorkers + 2;
-    if (nbJobs > mtctx->jobIDMask+1) {  /* need more job capacity */
-        ZSTDMT_freeJobsTable(mtctx->jobs, mtctx->jobIDMask+1, mtctx->cMem);
-        mtctx->jobIDMask = 0;
-        mtctx->jobs = ZSTDMT_createJobsTable(&nbJobs, mtctx->cMem);
-        if (mtctx->jobs==NULL) return ERROR(memory_allocation);
-        assert((nbJobs != 0) && ((nbJobs & (nbJobs - 1)) == 0));  /* ensure nbJobs is a power of 2 */
-        mtctx->jobIDMask = nbJobs - 1;
-    }
-    return 0;
+    void* jobs = mtctx->jobs;
+    U32 jobIDMask = mtctx->jobIDMask;
+    size_t const error = ZSTDMT_rust_expandJobsTable(
+        &jobs, &jobIDMask, nbWorkers, sizeof(ZSTDMT_jobDescription),
+        mtctx->cMem, ZSTDMT_job_table_init_sync, ZSTDMT_job_table_destroy_sync);
+    mtctx->jobs = (ZSTDMT_jobDescription*)jobs;
+    mtctx->jobIDMask = jobIDMask;
+    return error;
 }