Add WeatherKit data source package

Implements @aris/data-source-weatherkit for fetching weather data from
Apple WeatherKit REST API.

- WeatherKitDataSource class implementing DataSource interface
- Feed items: current, hourly, daily, and alerts
- Priority adjustment based on weather conditions and alert severity
- Unit conversion (metric/imperial)
- Response validation with arktype
- Test fixtures from real API responses

Co-authored-by: Ona <no-reply@ona.com>

packages/aris-data-source-weatherkit/src/index.ts

@@ -0,0 +1,35 @@
+export {
+	WeatherKitDataSource,
+	Units,
+	type Units as UnitsType,
+	type WeatherKitDataSourceOptions,
+	type WeatherKitQueryConfig,
+} from "./data-source"
+
+export {
+	WeatherFeedItemType,
+	type WeatherFeedItemType as WeatherFeedItemTypeType,
+	type CurrentWeatherData,
+	type CurrentWeatherFeedItem,
+	type DailyWeatherData,
+	type DailyWeatherFeedItem,
+	type HourlyWeatherData,
+	type HourlyWeatherFeedItem,
+	type WeatherAlertData,
+	type WeatherAlertFeedItem,
+	type WeatherFeedItem,
+} from "./feed-items"
+
+export {
+	Severity,
+	Urgency,
+	Certainty,
+	PrecipitationType,
+	ConditionCode,
+	type Severity as SeverityType,
+	type Urgency as UrgencyType,
+	type Certainty as CertaintyType,
+	type PrecipitationType as PrecipitationTypeType,
+	type ConditionCode as ConditionCodeType,
+	type WeatherKitCredentials,
+} from "./weatherkit"