Add client-side summary calculation and lookup resolution from cache

- Add calculateSummaryFromKanban() to compute summary stats from cached kanban data
- Add refreshSummaryFromKanban() called after task CRUD operations
- Fix column name matching to use API format (e.g., "overdue_tasks" not "overdue")
- Fix tasksDueNextMonth to only include due_soon tasks (not upcoming)
- Update TaskResponse computed properties to resolve from DataManager cache
- Update iOS task cards to use computed properties for priority/frequency/category
- This enables API to skip preloading lookups for better performance

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

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

iosApp/iosApp/Helpers/WidgetDataManager.swift

@@ -273,10 +273,10 @@ final class WidgetDataManager {
                     id: Int(task.id),
                     title: task.title,
                     description: task.description_,
-                    priority: task.priority?.name ?? "",
+                    priority: task.priorityName ?? "",
                     inProgress: task.inProgress,
                     dueDate: task.effectiveDueDate, // Use effective date (nextDueDate if set, otherwise dueDate)
-                    category: task.category?.name ?? "",
+                    category: task.categoryName ?? "",
                     residenceName: "", // No longer available in API, residence lookup needed
                     isOverdue: column.name == "overdue_tasks"
                 )