feat: Enhance TV support and Daily Weather Forecast (w/ Air Quality)

- **Frontend (Flutter)**
    - Optimize for Google TV: Force Landscape mode, disable touchscreen requirement, and set TV Dashboard as default home.
    - Weather Widget:
        - Add Daily Max/Min temperature ('최고/최저').
        - Add Air Quality Index (AQI) with visual indicator ('미세먼지').
        - Increase font sizes and adjust layout to match Digital Clock style.
        - Implement 1-hour auto-refresh timer.
    - Model: Update WeatherInfo to support tempMin, tempMax, and aqi.

- **Backend (Node.js)**
    - Weather API (/api/weather):
        - Implement daily forecast aggregation logic (Seoul Time KST) to calculate accurate daily High/Low.
        - Integrate OpenWeatherMap Air Pollution API to fetch AQI.

flutter_app/lib/models/weather_info.dart

@@ -1,12 +1,18 @@
 class WeatherInfo {
   final String description;
   final double temperature;
+  final double tempMin;
+  final double tempMax;
+  final int aqi;
   final String icon;
   final String city;
 
   const WeatherInfo({
     required this.description,
     required this.temperature,
+    required this.tempMin,
+    required this.tempMax,
+    required this.aqi,
     required this.icon,
     required this.city,
   });
@@ -18,6 +24,9 @@ class WeatherInfo {
     return WeatherInfo(
       description: weather["description"] as String? ?? "",
       temperature: (json["main"]?["temp"] as num?)?.toDouble() ?? 0,
+      tempMin: (json["main"]?["temp_min"] as num?)?.toDouble() ?? 0,
+      tempMax: (json["main"]?["temp_max"] as num?)?.toDouble() ?? 0,
+      aqi: json["aqi"] as int? ?? 0,
       icon: weather["icon"] as String? ?? "",
       city: json["name"] as String? ?? "",
     );