refactor(compress): move job table init policy to Rust

Keep job table allocation, private synchronization callbacks, and
initialization-failure cleanup in one Rust adapter. The C wrapper now only
supplies pthread/object callbacks, preserving rounded capacity and the
destroy-before-custom-free ordering; table expansion reuses the same path.

Test Plan:
- rustfmt --check --edition 2021 rust/src/zstdmt_compress.rs
- git diff --check and git diff --cached --check
- Static inspection only; cargo, make, tests, fuzzers, and native/heavy
  commands were not run under the global 40 GiB cap.

lib/compress/zstdmt_compress.c

@@ -666,6 +666,9 @@ typedef int (*ZSTDMT_jobTableInitFn)(void* jobTable, unsigned nbJobs,
                                      size_t jobSize);
 typedef void (*ZSTDMT_jobTableDestroyFn)(void* jobTable, unsigned nbJobs,
                                          size_t jobSize);
+void* ZSTDMT_rust_createJobsTable(
+        unsigned* nbJobsPtr, size_t jobSize, ZSTD_customMem cMem,
+        ZSTDMT_jobTableInitFn initSync, ZSTDMT_jobTableDestroyFn destroySync);
 size_t ZSTDMT_rust_expandJobsTable(
         void** jobTablePtr, unsigned* jobIDMaskPtr, unsigned nbWorkers,
         size_t jobSize, ZSTD_customMem cMem,
@@ -1753,14 +1756,9 @@ void ZSTDMT_job_table_destroy_sync(void* jobTable, unsigned nbJobs, size_t jobSi
  * update *nbJobsPtr to next power of 2 value, as size of table */
 static ZSTDMT_jobDescription* ZSTDMT_createJobsTable(U32* nbJobsPtr, ZSTD_customMem cMem)
 {
-    ZSTDMT_jobDescription* const jobTable = (ZSTDMT_jobDescription*)
-        ZSTDMT_rust_job_table_create(nbJobsPtr, sizeof(ZSTDMT_jobDescription), cMem);
-    if (jobTable == NULL) return NULL;
-    if (ZSTDMT_job_table_init_sync(jobTable, *nbJobsPtr, sizeof(*jobTable)) != 0) {
-        ZSTDMT_freeJobsTable(jobTable, *nbJobsPtr, cMem);
-        return NULL;
-    }
-    return jobTable;
+    return (ZSTDMT_jobDescription*) ZSTDMT_rust_createJobsTable(
+        nbJobsPtr, sizeof(ZSTDMT_jobDescription), cMem,
+        ZSTDMT_job_table_init_sync, ZSTDMT_job_table_destroy_sync);
 }
 
 static size_t ZSTDMT_expandJobsTable (ZSTDMT_CCtx* mtctx, U32 nbWorkers) {