Fix hourly curve alignment with forecast cell centers

The curve points were being distributed from x=0 to x=totalWidth using
a step calculation, causing misalignment with the HStack cells which
center their content at (index + 0.5) * cellWidth. Changed the x-coordinate
calculation to match the cell center positions, aligning temperature dots
with their corresponding hour labels and icons.

Author: cursoragent

example_projects/Weather/Weather/Views/Sections/HourlyForecastCard.swift

@@ -100,13 +100,13 @@ private struct HourlyCurve: View {
         let minTemp = temperatures.min() ?? 0
         let maxTemp = temperatures.max() ?? minTemp + 1
         let range = max(maxTemp - minTemp, 1)
-        let step = size.width / CGFloat(max(forecasts.count - 1, 1))
+        let cellWidth = size.width / CGFloat(forecasts.count)
         let pad: CGFloat = 8
 
         return forecasts.enumerated().map { index, forecast in
             let normalized = CGFloat(forecast.temperatureC - minTemp) / CGFloat(range)
             return CGPoint(
-                x: CGFloat(index) * step,
+                x: (CGFloat(index) + 0.5) * cellWidth,
                 y: pad + (1 - normalized) * (size.height - pad * 2)
             )
         }