Overlay: build the n-gram table parameter on the meta device when VLLM_PLE_QUANT_DIR is set, and swap the stub Parameter instead of set_data — removes the 102 GB virtual reservation that the kernel's overcommit heuristic refuses on hosts with less RAM+swap than the table (field report, 64 GB host); validated under an emulated 67/99 GiB commit limit, sanity PASS, tool-calling 77.0 (n=3), 81 tok/s c1
