feat: make site prefix column sortable

Clicking the Prefix column header sorts device and rack lists by site
name, which starts with the prefix.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

netbox_utilities/site_prefix.py

@@ -104,7 +104,8 @@ def install_site_prefix_column():
         accessor=tables.A("site"),
         verbose_name="Prefix",
         empty_values=(),
-        orderable=False,
+        # Der Standortname beginnt mit dem Prefix, sortiert also in derselben Reihenfolge.
+        order_by=("site__name",),
     )
     register_table_column(column, COLUMN_NAME, DeviceTable, RackTable)
     prepend_to_default_columns(DeviceTable)

netbox_utilities/tests/test_site_prefix.py

@@ -74,5 +74,9 @@ class SitePrefixTest(SimpleTestCase):
 
         self.assertIn(COLUMN_NAME, DeviceTable.base_columns)
         self.assertIn(COLUMN_NAME, RackTable.base_columns)
+        for table in (DeviceTable, RackTable):
+            column = table.base_columns[COLUMN_NAME]
+            self.assertTrue(column.orderable)
+            self.assertEqual(tuple(column.order_by), ("site__name",))
         self.assertEqual(DeviceTable.Meta.default_columns[:2], ("pk", COLUMN_NAME))
         self.assertEqual(RackTable.Meta.default_columns[:2], ("pk", COLUMN_NAME))