feat: Add Python class inheritance extraction for superclass relationships

Addresses Python's class definition syntax where parent classes are specified in argument_list nodes (e.g. `class Child(Parent, Mixin):`). Extracts identifier and attribute children from argument_list as 'extends' references to properly model Python's inheritance patterns in the code graph.

debug_python_ast2.js

@@ -0,0 +1,26 @@
+const { getParser, initGrammars, loadAllGrammars } = require('./dist/extraction/grammars');
+
+(async () => {
+  await initGrammars();
+  await loadAllGrammars();
+
+  const parser = getParser('python');
+
+  const code = `class Child(Parent, Mixin, Base):
+    pass`;
+
+  const tree = parser.parse(code);
+
+  function walk(node, depth = 0) {
+    const indent = '  '.repeat(depth);
+    const preview = node.text.substring(0, 40).replace(/\n/g, '\\n');
+    console.log(`${indent}${node.type} "${preview}"`);
+    
+    for (let i = 0; i < node.namedChildCount; i++) {
+      const child = node.namedChild(i);
+      if (child) walk(child, depth + 1);
+    }
+  }
+
+  walk(tree.rootNode);
+})();