Intl.DateTimeFormat: support Temporal types in format/formatRange

- Add IntlDateTimeInput enum to dispatch Legacy, Instant, and Plain Temporal inputs
- Add IntlTemporalDateTimeKind and IntlTemporalDateTimeFields structs for Temporal field representation
- Add intl_temporal_fields_from_{date,datetime,time,year_month,month_day} converters
- Add intl_date_time_format_input / intl_date_time_format_required_input dispatchers
- Add intl_temporal_normalized_formatter, intl_temporal_instant_formatter helpers
- Add intl_date_time_format_parts_for_temporal and intl_temporal_style_parts for Temporal-aware rendering
- Add intl_date_time_range_parts_from_values and intl_can_collapse_date_time_range_prefix for range formatting
- Update format/formatToParts/formatRange/formatRangeToParts to handle all Temporal types
- Add kind-mismatch check in formatRange for mixed Temporal/non-Temporal arguments
- Expose temporal_expect_{instant,plain_date,plain_date_time,plain_time,year_month,month_day} as pub(super)
- Add temporal_value_kind helper to identify Temporal object kind
- Wire all Temporal toLocaleString methods to Intl.DateTimeFormat with locale/options args
- Add temporal_instant_to_locale_string and temporal_duration_to_locale_string helpers
- Fix date.rs needs_defaults to account for dateStyle/timeStyle options

Author: ssrlive

src/core/vm/date.rs

@@ -274,13 +274,17 @@ impl<'gc> VM<'gc> {
                 let value = self.read_named_property(ctx, &boxed_options, key);
                 self.pending_throw.is_none() && !matches!(value, Value::Undefined)
             });
+        let date_style = self.read_named_property(ctx, &boxed_options, "dateStyle");
+        let time_style = self.read_named_property(ctx, &boxed_options, "timeStyle");
         if let Some(thrown) = self.pending_throw.take() {
             return Err(thrown);
         }
+        let has_date_style = !matches!(date_style, Value::Undefined);
+        let has_time_style = !matches!(time_style, Value::Undefined);
         let needs_defaults = match mode {
-            "date" => !has_date_fields,
-            "time" => !has_time_fields,
-            _ => !has_date_fields && !has_time_fields,
+            "date" => !has_date_fields && !has_date_style,
+            "time" => !has_time_fields && !has_time_style,
+            _ => !has_date_fields && !has_time_fields && !has_date_style && !has_time_style,
         };
         if !needs_defaults {
             return Ok(vec![locales, boxed_options]);