feat(programs): move pass-through copying into Rust

Keep decompression resource ownership and file orchestration in C while the
Rust AIO module handles the pass-through byte-copy leaf through a two-pool ABI.
The Rust implementation derives the block limit from the actual read and write
job buffers, preventing a write-job overrun when their configured sizes differ.
It preserves the existing enqueue/reacquire, consume/refill, EOF, release, and
sparse-write ordering, with pool-backed coverage for synchronous and threaded
operation.

Test Plan:
- `cargo test --manifest-path rust/Cargo.toml --no-default-features --features compression --lib fileio_asyncio` -- passed, 9 tests.
- Required clippy/fmt sequence against `rust/Cargo.toml` with compression -- passed before and after nightly fmt.
- `cargo test --manifest-path rust/Cargo.toml --no-default-features --features compression --lib` -- passed, 342 tests.
- `make -C programs -j2 zstd` -- passed.
- Manual 200 KiB and empty-input `programs/zstd -dc --pass-through` comparisons -- passed.

programs/fileio.c

@@ -343,6 +343,7 @@ int FIO_rust_setDictBufferMalloc(const char* fileName,
                                  void** buffer,
                                  size_t* loadedSize);
 int FIO_rust_removeFile(const char* path);
+int FIO_rust_passThrough(ReadPoolCtx_t* readCtx, WritePoolCtx_t* writeCtx);
 #ifdef ZSTD_LZ4COMPRESS
 int FIO_rust_LZ4_GetBlockSize_FromBlockId(int id);
 #endif
@@ -2123,24 +2124,7 @@ static void FIO_freeDResources(dRess_t ress)
  * @return : 0 (no error) */
 static int FIO_passThrough(dRess_t *ress)
 {
-    size_t const blockSize = MIN(MIN(64 KB, ZSTD_DStreamInSize()), ZSTD_DStreamOutSize());
-    IOJob_t *writeJob = AIO_WritePool_acquireJob(ress->writeCtx);
-    AIO_ReadPool_fillBuffer(ress->readCtx, blockSize);
-
-    while(ress->readCtx->srcBufferLoaded) {
-        size_t writeSize;
-        writeSize = MIN(blockSize, ress->readCtx->srcBufferLoaded);
-        assert(writeSize <= writeJob->bufferSize);
-        memcpy(writeJob->buffer, ress->readCtx->srcBuffer, writeSize);
-        writeJob->usedBufferSize = writeSize;
-        AIO_WritePool_enqueueAndReacquireWriteJob(&writeJob);
-        AIO_ReadPool_consumeBytes(ress->readCtx, writeSize);
-        AIO_ReadPool_fillBuffer(ress->readCtx, blockSize);
-    }
-    assert(ress->readCtx->reachedEof);
-    AIO_WritePool_releaseIoJob(writeJob);
-    AIO_WritePool_sparseWriteEnd(ress->writeCtx);
-    return 0;
+    return FIO_rust_passThrough(ress->readCtx, ress->writeCtx);
 }
 
 /* FIO_zstdErrorHelp() :