Add comprehensive WCAG 2.1 AA accessibility support

- Add VoiceOver labels and hints to all voting layouts, settings, widgets,
  onboarding screens, and entry cells
- Add Reduce Motion support to button animations throughout the app
- Ensure 44x44pt minimum touch targets on widget mood buttons
- Enhance AccessibilityHelpers with Dynamic Type support, ScaledValue wrapper,
  and VoiceOver detection utilities
- Gate premium features (Insights, Month/Year views) behind subscription
- Update widgets to show subscription prompts for non-subscribers

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

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

Shared/Onboarding/views/OnboardingWelcome.swift

@@ -71,6 +71,8 @@ struct OnboardingWelcome: View {
                         .foregroundColor(.white.opacity(0.7))
                 }
                 .padding(.bottom, 60)
+                .accessibilityLabel(String(localized: "Swipe right to continue"))
+                .accessibilityHint(String(localized: "Swipe to the next onboarding step"))
             }
         }
     }
@@ -92,6 +94,7 @@ struct FeatureRow: View {
                     .font(.system(size: 22))
                     .foregroundColor(.white)
             }
+            .accessibilityHidden(true)
 
             VStack(alignment: .leading, spacing: 2) {
                 Text(title)
@@ -105,6 +108,8 @@ struct FeatureRow: View {
 
             Spacer()
         }
+        .accessibilityElement(children: .combine)
+        .accessibilityLabel("\(title): \(description)")
     }
 }