Add nextDueDate field to TaskResponse for recurring task support

- Add nextDueDate field to TaskResponse model (from API's next_due_date)
- Add effectiveDueDate computed property (nextDueDate ?? dueDate)
- Update DynamicTaskCard, TaskCard to display effectiveDueDate
- Update WidgetDataManager to save effectiveDueDate to widget cache
- Update TaskFormView to use effectiveDueDate when editing
- Fix preview mock data to include nextDueDate parameter

This ensures recurring tasks show the correct next due date after completion
instead of the original due date.

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

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

composeApp/src/commonMain/kotlin/com/example/casera/models/CustomTask.kt

@@ -44,6 +44,7 @@ data class TaskResponse(
     @SerialName("frequency_id") val frequencyId: Int? = null,
     val frequency: TaskFrequency? = null,
     @SerialName("due_date") val dueDate: String? = null,
+    @SerialName("next_due_date") val nextDueDate: String? = null, // For recurring tasks, updated after each completion
     @SerialName("estimated_cost") val estimatedCost: Double? = null,
     @SerialName("actual_cost") val actualCost: Double? = null,
     @SerialName("contractor_id") val contractorId: Int? = null,
@@ -74,8 +75,11 @@ data class TaskResponse(
     val priorityName: String? get() = priority?.name
     val priorityDisplayName: String? get() = priority?.displayName
 
+    // Effective due date: use nextDueDate if set (for recurring tasks), otherwise use dueDate
+    val effectiveDueDate: String? get() = nextDueDate ?: dueDate
+
     // Fields that don't exist in Go API - return null/default
-    val nextScheduledDate: String? get() = null  // Would need calculation based on frequency
+    val nextScheduledDate: String? get() = nextDueDate  // Now we have this from the API
     val showCompletedButton: Boolean get() = true // Always show complete button since status is now just in_progress boolean
     val daySpan: Int? get() = frequency?.days
     val notifyDays: Int? get() = null  // Not in Go API

iosApp/iosApp/Helpers/WidgetDataManager.swift

@@ -275,7 +275,7 @@ final class WidgetDataManager {
                     description: task.description_,
                     priority: task.priority?.name ?? "",
                     inProgress: task.inProgress,
-                    dueDate: task.dueDate,
+                    dueDate: task.effectiveDueDate, // Use effective date (nextDueDate if set, otherwise dueDate)
                     category: task.category?.name ?? "",
                     residenceName: "", // No longer available in API, residence lookup needed
                     isOverdue: column.name == "overdue_tasks"

iosApp/iosApp/Subviews/Task/DynamicTaskCard.swift

@@ -49,8 +49,8 @@ struct DynamicTaskCard: View {
 
                 Spacer()
 
-                if let due_date = task.dueDate {
-                    Label(DateUtils.formatDate(due_date), systemImage: "calendar")
+                if let effectiveDate = task.effectiveDueDate {
+                    Label(DateUtils.formatDate(effectiveDate), systemImage: "calendar")
                         .font(.caption)
                         .foregroundColor(Color.appTextSecondary)
                 }

iosApp/iosApp/Subviews/Task/TaskCard.swift

@@ -58,12 +58,12 @@ struct TaskCard: View {
 
                 Spacer()
 
-                if let dueDate = task.dueDate {
+                if let effectiveDate = task.effectiveDueDate {
                     HStack(spacing: AppSpacing.xxs) {
                         Image(systemName: "calendar")
                             .font(.system(size: 12, weight: .medium))
                             .foregroundColor(Color.appTextSecondary.opacity(0.7))
-                        Text(DateUtils.formatDate(dueDate))
+                        Text(DateUtils.formatDate(effectiveDate))
                             .font(.caption.weight(.medium))
                             .foregroundColor(Color.appTextSecondary)
                     }
@@ -262,6 +262,7 @@ struct TaskCard: View {
                 frequencyId: 1,
                 frequency: TaskFrequency(id: 1, name: "monthly", days: 30, displayOrder: 0),
                 dueDate: "2024-12-15",
+                nextDueDate: nil,
                 estimatedCost: 150.00,
                 actualCost: nil,
                 contractorId: nil,

iosApp/iosApp/Subviews/Task/TasksSection.swift

@@ -96,6 +96,7 @@ struct TasksSection: View {
                             frequencyId: 1,
                             frequency: TaskFrequency(id: 1, name: "monthly", days: 30, displayOrder: 0),
                             dueDate: "2024-12-15",
+                            nextDueDate: nil,
                             estimatedCost: 150.00,
                             actualCost: nil,
                             contractorId: nil,
@@ -135,6 +136,7 @@ struct TasksSection: View {
                             frequencyId: 6,
                             frequency: TaskFrequency(id: 6, name: "once", days: nil, displayOrder: 0),
                             dueDate: "2024-11-01",
+                            nextDueDate: nil,
                             estimatedCost: 200.00,
                             actualCost: nil,
                             contractorId: nil,

iosApp/iosApp/Task/TaskFormView.swift

@@ -66,10 +66,10 @@ struct TaskFormView: View {
             _selectedPriority = State(initialValue: task.priority)
             _inProgress = State(initialValue: task.inProgress)
 
-            // Parse date from string
+            // Parse date from string - use effective due date (nextDueDate if set, otherwise dueDate)
             let formatter = DateFormatter()
             formatter.dateFormat = "yyyy-MM-dd"
-            _dueDate = State(initialValue: formatter.date(from: task.dueDate ?? "") ?? Date())
+            _dueDate = State(initialValue: formatter.date(from: task.effectiveDueDate ?? "") ?? Date())
 
             _intervalDays = State(initialValue: "")  // No longer in API
             _estimatedCost = State(initialValue: task.estimatedCost != nil ? String(task.estimatedCost!.doubleValue) : "")