add nix build test

Author: Anton-4

.github/workflows/ci_zig.yml

@@ -219,6 +219,12 @@ jobs:
           git reset --hard HEAD
           nix develop ./src/ -c zig build && zig build snapshot && zig build test
 
+      - name: Test nix package
+        if: ${{ runner.os == 'Linux' || (runner.os == 'macOS' && runner.arch != 'X64') }}
+        run: |
+          nix build ./src/#roc
+          ./result/bin/roc check src/PROFILING/bench_repeated_check.roc
+
   zig-cross-compile:
     needs: check-once
     runs-on: ubuntu-24.04