Fix widget layout clipping and add comprehensive widget previews

- Fix LargeVotingView mood icons getting clipped at edges by using
  flexible HStack spacing with maxWidth: .infinity
- Fix VotingView medium layout with smaller icons and even distribution
- Add comprehensive #Preview macros for all widget states:
  - Vote widget: small/medium, voted/not voted, all mood states
  - Timeline widget: small/medium/large with various data states
- Reduce icon sizes and padding to fit within widget bounds
- Update accessibility labels and hints across views

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

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

Shared/Onboarding/views/OnboardingWelcome.swift

@@ -32,20 +32,20 @@ struct OnboardingWelcome: View {
                         .frame(width: 120, height: 120)
 
                     Image(systemName: "heart.fill")
-                        .font(.system(size: 50))
+                        .font(.largeTitle)
                         .foregroundColor(.white)
                 }
                 .padding(.bottom, 40)
 
                 // Title
                 Text("Welcome to Feels")
-                    .font(.system(size: 34, weight: .bold, design: .rounded))
+                    .font(.largeTitle.weight(.bold))
                     .foregroundColor(.white)
                     .padding(.bottom, 12)
 
                 // Subtitle
                 Text("Track your mood, discover patterns,\nand understand yourself better.")
-                    .font(.system(size: 18, weight: .medium))
+                    .font(.headline.weight(.medium))
                     .foregroundColor(.white.opacity(0.9))
                     .multilineTextAlignment(.center)
                     .padding(.horizontal, 40)
@@ -91,18 +91,18 @@ struct FeatureRow: View {
                     .frame(width: 50, height: 50)
 
                 Image(systemName: icon)
-                    .font(.system(size: 22))
+                    .font(.title3)
                     .foregroundColor(.white)
             }
             .accessibilityHidden(true)
 
             VStack(alignment: .leading, spacing: 2) {
                 Text(title)
-                    .font(.system(size: 16, weight: .semibold))
+                    .font(.body.weight(.semibold))
                     .foregroundColor(.white)
 
                 Text(description)
-                    .font(.system(size: 14))
+                    .font(.subheadline)
                     .foregroundColor(.white.opacity(0.8))
             }