feat: enforce custom Theme colors app-wide, add debug sample trips and poll

Replace all system colors (.secondary, Color(.secondarySystemBackground),
etc.) with Theme.textPrimary/textSecondary/textMuted/cardBackground/
surfaceGlow across 13 views. Remove PostHog debug logging. Add debug
settings for sample trips and hardcoded group poll preview.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

SportsTime/Features/Progress/Views/StadiumVisitHistoryView.swift

@@ -65,6 +65,7 @@ struct StadiumVisitHistoryView: View {
 }
 
 private struct VisitHistoryList: View {
+    @Environment(\.colorScheme) private var colorScheme
     let visits: [StadiumVisit]
 
     var body: some View {
@@ -74,6 +75,7 @@ private struct VisitHistoryList: View {
                 HStack {
                     Text("\(visits.count) Visit\(visits.count == 1 ? "" : "s")")
                         .font(.headline)
+                        .foregroundStyle(Theme.textPrimary(colorScheme))
                     Spacer()
                 }
                 .padding(.horizontal)
@@ -86,23 +88,26 @@ private struct VisitHistoryList: View {
             }
             .padding(.vertical)
         }
-        .background(Color(.systemGroupedBackground))
+        .background(Theme.backgroundGradient(colorScheme))
     }
 }
 
 private struct EmptyVisitHistoryView: View {
+    @Environment(\.colorScheme) private var colorScheme
+
     var body: some View {
         VStack(spacing: 16) {
             Image(systemName: "calendar.badge.plus")
                 .font(.largeTitle)
-                .foregroundStyle(.secondary)
+                .foregroundStyle(Theme.textMuted(colorScheme))
 
             Text("No visits recorded")
                 .font(.headline)
+                .foregroundStyle(Theme.textPrimary(colorScheme))
 
             Text("Tap + to add your first visit to this stadium")
                 .font(.subheadline)
-                .foregroundStyle(.secondary)
+                .foregroundStyle(Theme.textSecondary(colorScheme))
                 .multilineTextAlignment(.center)
         }
         .padding()