Fixes #22441: Address claudebot review feedback

- humanize_duration: guard on 'is None' instead of falsiness so
  timedelta(0) renders as '0s' rather than blank
- execution_time filter: add label= for consistency with sibling filters

netbox/core/filtersets.py

@@ -132,7 +132,9 @@ class JobFilterSet(BaseFilterSet):
         field_name='completed',
         lookup_expr='gte'
     )
-    execution_time = django_filters.DurationFilter()
+    execution_time = django_filters.DurationFilter(
+        label=_('Execution time')
+    )
     execution_time__gte = django_filters.DurationFilter(
         field_name='execution_time',
         lookup_expr='gte',

netbox/utilities/string.py

@@ -12,9 +12,9 @@ __all__ = (
 def humanize_duration(value):
     """
     Express a timedelta in a human-friendly format. Example: 1h 5m 23s. Returns an empty string
-    for a null or zero-length duration.
+    for None; zero-duration timedeltas render as "0s".
     """
-    if not value:
+    if value is None:
         return ''
 
     # Round to whole seconds and decompose

netbox/utilities/tests/test_string.py

@@ -7,9 +7,11 @@ from utilities.string import humanize_duration
 
 class HumanizeDurationTest(TestCase):
 
-    def test_none_and_zero(self):
+    def test_none(self):
         self.assertEqual(humanize_duration(None), '')
-        self.assertEqual(humanize_duration(timedelta(0)), '')
+
+    def test_zero_duration(self):
+        self.assertEqual(humanize_duration(timedelta(0)), '0s')
 
     def test_seconds_only(self):
         self.assertEqual(humanize_duration(timedelta(seconds=45)), '45s')