perf: reduce Go FFI allocations, harden lifecycle concurrency, and optimize native FTS ingestion / 优化 Go FFI 分配、加固生命周期并发与原生全文索引写入 - #15

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/setup-go@v5. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/