rust-toolchain.toml gains the x86_64-unknown-linux-musl target; the
flake devShell gains a musl cc (pkgsCross.musl64) + CC/linker env so a
`cargo build --target …-musl` compiles rusqlite's bundled SQLite C and
links fully static (D2: single static binary, no runtime deps). Cargo
release profile strips symbols (13MB -> 10MB). Verified locally: the
musl binary is static-pie, statically linked, stripped, runs standalone.
Root flake with two outputs: devShells.default (pinned 1.95.0
toolchain via rust-toolchain.toml + rust-overlay, plus cargo-sweep)
and packages.default (rustPlatform.buildRustPackage from the committed
Cargo.lock; doCheck=false). flake.lock pins nixpkgs nixos-26.05 /
rust-overlay / flake-utils. .envrc (use flake) for direnv parity.
Single source of toolchain for dev and the upcoming CI, so they can't
drift. Verified through the flake: nix build yields a working binary,
clippy clean, 2424 tests pass / 0 fail / 1 intentional ignored doctest.
First step toward requirements.md TT5 + D1/D2/D3.