Capture interface functions and record fields correctly in parser

Tests/SwiftGtkGenCoreTests/ParserTests.swift

@@ -196,6 +196,27 @@ func testParsingMissingAttributes() {
     }
 }
 
+@Test("Parser captures interface-level functions")
+func testInterfaceFunctions() throws {
+    let xml = """
+    <?xml version="1.0"?>
+    <repository xmlns="http://www.gtk.org/introspection/core/1.0">
+      <namespace name="Gtk" version="4.0">
+        <interface name="Buildable" c:type="GtkBuildable">
+          <function name="get_id" c:identifier="gtk_buildable_get_id">
+            <return-value><type name="utf8"/></return-value>
+          </function>
+        </interface>
+      </namespace>
+    </repository>
+    """
+    let repo = try GIRParser().parse(xmlString: xml)
+    let iface = repo.namespaces[0].interfaces[0]
+    #expect(iface.functions.count == 1)
+    #expect(iface.functions[0].name == "get_id")
+    #expect(iface.functions[0].cIdentifier == "gtk_buildable_get_id")
+}
+
 @Test("Parser rejects invalid XML")
 func testParsingError() {
     let parser = GIRParser()