Add ExerciseView with navigation and progress tracking

- Copy ExerciseView from Workouts_old, adapt for CoreData
- Add WeightProgressionChartView with historical weight data and chart
- Refactor CheckboxListItem to use Button for checkbox tap handling
- Update WorkoutLogListView to use NavigationLink for exercise details
- Checkbox taps now only cycle status, row tap navigates to exercise

Workouts/Views/Common/CheckboxListItem.swift

@@ -14,32 +14,39 @@ struct CheckboxListItem: View {
     var title: String
     var subtitle: String?
     var count: Int?
+    var onCheckboxTap: (() -> Void)? = nil
 
     var body: some View {
         HStack(alignment: .top) {
-            Image(systemName: status.systemName)
-                .resizable()
-                .scaledToFit()
-                .frame(width: 30)
-                .foregroundStyle(status.color)
+            Button {
+                onCheckboxTap?()
+            } label: {
+                Image(systemName: status.systemName)
+                    .resizable()
+                    .scaledToFit()
+                    .frame(width: 30, height: 30)
+                    .foregroundStyle(status.color)
+            }
+            .buttonStyle(.plain)
             VStack(alignment: .leading) {
                 Text("\(title)")
                     .font(.headline)
+                    .foregroundColor(.primary)
                 HStack(alignment: .bottom) {
                     if let subtitle = subtitle {
                         Text("\(subtitle)")
                             .font(.footnote)
+                            .foregroundColor(.secondary)
                     }
                 }
             }
+            Spacer()
             if let count = count {
-                Spacer()
                 Text("\(count)")
                     .font(.caption)
                     .foregroundColor(.gray)
             }
         }
         .frame(maxWidth: .infinity, alignment: .leading)
-        .contentShape(Rectangle())
     }
 }