Add Wolfram Language support via official LSPServer paclet (#1108)

Adds support for Wolfram Language (.wl, .wls files) using the official
WolframResearch LSPServer paclet, which communicates via stdio.
Requires Wolfram Mathematica 13.0+ or Wolfram Engine 12.1+.
The WolframKernel is located via WOLFRAM_PATH, the system PATH, common
install locations, or ls_path in ls_specific_settings.

Includes language server implementation, test repo, test suite
(skipped gracefully when WolframKernel is unavailable), and
documentation updates.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

test/solidlsp/wolfram/test_wolfram_basic.py

@@ -0,0 +1,66 @@
+import pytest
+
+from solidlsp.ls import SolidLanguageServer
+from solidlsp.ls_config import LanguageServerId
+from test.conftest import language_server_tests_enabled
+
+pytestmark = [
+    pytest.mark.wolfram,
+    pytest.mark.skipif(
+        not language_server_tests_enabled(LanguageServerId.WOLFRAM), reason="Wolfram tests disabled (WolframKernel not available)"
+    ),
+]
+
+# Note: the LSPServer paclet computes textDocument/references per document, i.e. only
+# references within the file containing the queried position are returned; cross-file
+# references are not supported by the language server.
+
+
+class TestWolframLanguageServer:
+    @pytest.mark.parametrize("language_server", [LanguageServerId.WOLFRAM], indirect=True)
+    def test_wolfram_symbols(self, language_server: SolidLanguageServer):
+        """
+        Test if we can find the top-level symbols in the main.wl file.
+        """
+        all_symbols, _ = language_server.request_document_symbols("main.wl").get_all_symbols_and_roots()
+        symbol_names = {s["name"] for s in all_symbols}
+        assert "calculateSum" in symbol_names
+        assert "main" in symbol_names
+
+    @pytest.mark.parametrize("language_server", [LanguageServerId.WOLFRAM], indirect=True)
+    def test_wolfram_symbols_in_subdirectory(self, language_server: SolidLanguageServer):
+        """
+        Test if we can find the top-level symbols in a file in a subdirectory.
+        """
+        all_symbols, _ = language_server.request_document_symbols("lib/helper.wl").get_all_symbols_and_roots()
+        symbol_names = {s["name"] for s in all_symbols}
+        assert "sayHello" in symbol_names
+        assert "formatResult" in symbol_names
+
+    @pytest.mark.parametrize("language_server", [LanguageServerId.WOLFRAM], indirect=True)
+    def test_wolfram_within_file_references(self, language_server: SolidLanguageServer):
+        """
+        Test finding references to a function within the same file.
+        """
+        # 'calculateSum' is defined on line 2 of main.wl and called on line 10 (0-based)
+        references = language_server.request_references("main.wl", line=2, column=0)
+
+        reference_lines = {(ref["relativePath"], ref["range"]["start"]["line"]) for ref in references}
+        assert ("main.wl", 2) in reference_lines, f"Expected the definition site among references, got {reference_lines}"
+        assert ("main.wl", 10) in reference_lines, f"Expected the call site among references, got {reference_lines}"
+
+    @pytest.mark.parametrize("language_server", [LanguageServerId.WOLFRAM], indirect=True)
+    def test_wolfram_no_cross_file_references(self, language_server: SolidLanguageServer):
+        """
+        Test documenting that references are computed per document by the LSPServer paclet.
+
+        'sayHello' is defined in lib/helper.wl and called in main.wl, but querying references
+        from its definition must only return locations within lib/helper.wl. If this test
+        starts failing, the language server gained cross-file reference support and the
+        documentation (docs page, CHANGELOG, module comment above) should be updated.
+        """
+        references = language_server.request_references("lib/helper.wl", line=0, column=0)
+
+        assert references, "Expected at least one within-file reference in lib/helper.wl fixture"
+        reference_paths = {ref["relativePath"] for ref in references}
+        assert reference_paths == {"lib/helper.wl"}, f"Expected references only within lib/helper.wl, got {reference_paths}"