feat: add news ticker widget for scrolling headlines

- Add NewsTickerWidget with horizontal auto-scrolling at 40px/sec
- Add NewsData and NewsHeadline Freezed models
- Add news datasource fetching from /tools/news endpoint
- Add news provider with 30-minute auto-refresh
- Place ticker between Welcome card and System Stats on dashboard
- Show placeholder headlines when no data (italic, muted style)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

lib/shared/widgets/weather_widget.dart

@@ -76,11 +76,11 @@ class WeatherWidget extends StatelessWidget {
               height: 170,
               child: Stack(
                 children: [
-                  // Main content positioned above horizon
+                  // Main content positioned above horizon (8px gap)
                   Positioned(
                     left: 0,
                     right: 0,
-                    bottom: 50,
+                    bottom: 58,
                     child: Row(
                       children: [
                         // Weather icon in box
@@ -145,12 +145,12 @@ class WeatherWidget extends StatelessWidget {
                       ],
                     ),
                   ),
-                  // Horizon divider at fixed position
+                  // Horizon divider at fixed position (matches Sun Position horizonY)
                   if (weather.humidity != null || weather.windSpeed != null)
                     Positioned(
                       left: 0,
                       right: 0,
-                      bottom: 38,
+                      bottom: 50,
                       child: const Divider(height: 1),
                     ),
                   // Footer below horizon