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/index.ts

@@ -953,6 +953,11 @@ export class CodeGraph {
     return this.queries.getNodesByName(name);
   }
 
+  /** Nodes whose name starts with `prefix` (index range scan, capped). */
+  getNodesByNamePrefix(prefix: string, limit = 20): Node[] {
+    return this.queries.getNodesByNamePrefix(prefix, limit);
+  }
+
   /**
    * Search nodes by text
    */