Replace modernc with go-sqlite3 v1.14.52 and its bundled SQLite 3.53.4 engine. Enable CGO and provide a C compiler in the Nix development environment. Update the vendor hash and build docs. Keep schema 12, storage interfaces, cache configuration, WAL/NORMAL durability, index deferral, and atomic replay checkpoints unchanged. A modernc database probe retains records, comments, tags, thresholds, secret blobs, tombstones, and deferred indexes, then resumes replay. Local benchmarks show 27-32% higher throughput and 26-38% lower RSS. Production effects remain unmeasured. Race tests, vet, SQL checks, both Nix service builds, and NixOS module checks pass. tsk-46