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/Task/CompleteTaskView.swift

@@ -33,7 +33,7 @@ struct CompleteTaskView: View {
                             .font(.headline)
 
                         HStack {
-                            Label((task.category?.name ?? "").capitalized, systemImage: "folder")
+                            Label((task.categoryName ?? "").capitalized, systemImage: "folder")
                                 .font(.subheadline)
                                 .foregroundStyle(.secondary)