ci: add nvim feature to test matrices

Extend CI workflow to include the nvim devcontainer feature in both
test-autogenerated and test-scenarios job matrices.

Ensures comprehensive testing coverage for the newly added nvim feature.

Author: iamralch

.github/workflows/ci.yaml

@@ -15,6 +15,7 @@ jobs:
           - atlas
           - starship
           - opencode
+          - nvim
         baseImage:
           - debian:latest
           - ubuntu:latest
@@ -34,6 +35,7 @@ jobs:
           - atlas
           - starship
           - opencode
+          - nvim
     steps:
       - uses: actions/checkout@v4
       - name: "Install latest devcontainer CLI"