Add enable_millisecond to duration selector (#122821)

* Add enable_milliseconds to duration selector.

* One more test

homeassistant/helpers/selector.py

@@ -725,6 +725,7 @@ class DurationSelectorConfig(TypedDict, total=False):
     """Class to represent a duration selector config."""
 
     enable_day: bool
+    enable_millisecond: bool
     allow_negative: bool
 
 
@@ -739,6 +740,8 @@ class DurationSelector(Selector[DurationSelectorConfig]):
             # Enable day field in frontend. A selection with `days` set is allowed
             # even if `enable_day` is not set
             vol.Optional("enable_day"): cv.boolean,
+            # Enable millisecond field in frontend.
+            vol.Optional("enable_millisecond"): cv.boolean,
             # Allow negative durations. Will default to False in HA Core 2025.6.0.
             vol.Optional("allow_negative"): cv.boolean,
         }

tests/helpers/test_selector.py

@@ -739,12 +739,13 @@ def test_attribute_selector_schema(
             (
                 {"seconds": 10},
                 {"days": 10},  # Days is allowed also if `enable_day` is not set
+                {"milliseconds": 500},
             ),
             (None, {}),
         ),
         (
-            {"enable_day": True},
+            {"enable_day": True, "enable_millisecond": True},
-            ({"seconds": 10}, {"days": 10}),
+            ({"seconds": 10}, {"days": 10}, {"milliseconds": 500}),
             (None, {}),
         ),
         (