fix(scala): emit field type references for var declarations

The Scala field handler matched only `val_definition`, so a mutable field
(`var b: Repo`), which parses as `var_definition`, had its type reference
silently dropped from the graph. val and var nodes are structurally identical
(both expose a `type` field), so the existing type-collection logic works
unchanged. Widen the guard to accept var_definition.

Adds a var field to the Scala fixture and a regression test.

graphify/extract.py

@@ -3868,7 +3868,7 @@ def _extract_generic(
             return
 
         if (config.ts_module == "tree_sitter_scala"
-                and t == "val_definition"
+                and t in ("val_definition", "var_definition")
                 and parent_class_nid):
             type_node = node.child_by_field_name("type")
             if type_node is not None:

tests/fixtures/sample.scala

@@ -7,6 +7,7 @@ abstract class BaseClient
 
 class HttpClient(config: Config) extends BaseClient with Loggable {
   val source: Config = config
+  var fallback: BaseClient = null
 
   def get(path: String): String = {
     buildRequest("GET", path)

tests/test_languages.py

@@ -655,6 +655,11 @@ def test_scala_val_definition_field_context():
     assert ("HttpClient", "Config") in _edge_labels(r, "references", "field")
 
 
+def test_scala_var_definition_field_context():
+    r = extract_scala(FIXTURES / "sample.scala")
+    assert ("HttpClient", "BaseClient") in _edge_labels(r, "references", "field")
+
+
 def test_scala_method_return_type_context():
     r = extract_scala(FIXTURES / "sample.scala")
     assert ("create", "HttpClient") in _edge_labels(r, "references", "return_type")