feat(extraction): add Nix language support with module-system option wiring (#324, #332 via #648 — carries #1084) (#1190)

Carries @TyceHerrman's #1084 as the functional base. Extraction + file wiring (imports/modules lists, callPackage), module-system option-path synthesizer, lexical-scope resolution gates, ABI-15 wasm rebuilt from upstream source. Validated on agenix, nix-darwin, home-manager, and nixpkgs (44,368 files, 3m49s, 1.30M nodes).

Co-authored-by: Tyce Herrman <Tyce.Herrman@pm.me>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

src/types.ts

@@ -93,6 +93,7 @@ export const LANGUAGES = [
   'objc',
   'r',
   'solidity',
+  'nix',
   'yaml',
   'twig',
   'xml',