docs: add zh-cn SPDK architecture doc

[LJF-050]

Summary

• Add the zh-cn translation for the SPDK integration architecture document.
• Keep the original structure, Mermaid diagrams, code references, and SPDK reference link.
• Cover SPDK environment, poller, FFI layer, qpair pool, DMA buffer management, read/write paths, and block lifecycle.

Test

• npm run build