feat: Add comprehensive OCaml language support with ocaml-lsp-server integration (#573)

.github/workflows/pytest.yml

@@ -199,6 +199,23 @@ jobs:
       - name: Install Ruby language server
         shell: bash
         run: gem install ruby-lsp
+      - name: Install OCaml and opam
+        uses: ocaml/setup-ocaml@v3
+        with:
+          ocaml-compiler: ${{ runner.os == 'Windows' && '4.14' || '5.3.x' }}
+          dune-cache: true
+          opam-repositories: |
+            ${{ runner.os == 'Windows' && 'opam-repository-mingw: https://github.com/ocaml-opam/opam-repository-mingw.git#sunset' || '' }}
+            default: https://github.com/ocaml/opam-repository.git
+      - name: Install OCaml packages
+        shell: bash
+        run: |
+          if [ "$RUNNER_OS" = "Windows" ]; then
+            opam install -y dune ocaml-lsp-server
+          else
+            # Require ocaml-lsp-server >= 1.23.0 for cross-file reference support
+            opam install -y dune 'ocaml-lsp-server>=1.23.0'
+          fi
       - name: Install R
         uses: r-lib/actions/setup-r@v2
         with: