Add photo viewer for task completions on iOS and Android

- Add PhotoViewerDialog (Android) and PhotoViewerSheet (iOS) for viewing completion photos
- Add CompletionCardView (iOS) to display completion details with photo button
- Update AllTasksView (iOS) to show full completion details instead of just count
- Update TaskCard (Android) to use CompletionCard component
- Add Coil 3.0.4 image loading library for Android
- Configure ImageLoader in MainActivity with network, memory, and disk caching
- Add getMediaBaseUrl() to ApiClient for loading media files without /api path
- Fix photo viewer background color to match app theme

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

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

iosApp/iosApp/Task/AllTasksView.swift

@@ -330,13 +330,19 @@ struct DynamicTaskCard: View {
             
             if task.completions.count > 0 {
                 Divider()
-                
-                HStack {
-                    Image(systemName: "checkmark.circle")
-                        .foregroundColor(.green)
-                    Text("Completed \(task.completions.count) time\(task.completions.count == 1 ? "" : "s")")
-                        .font(.caption)
-                        .foregroundColor(.secondary)
+
+                VStack(alignment: .leading, spacing: 8) {
+                    HStack {
+                        Image(systemName: "checkmark.circle.fill")
+                            .foregroundColor(.green)
+                        Text("Completions (\(task.completions.count))")
+                            .font(.caption)
+                            .fontWeight(.semibold)
+                    }
+
+                    ForEach(task.completions, id: \.id) { completion in
+                        CompletionCardView(completion: completion)
+                    }
                 }
             }