ios: TaskViewModel observes $allTasks and filters by residence in-memory

Replaces the dual-sink ($allTasks when residence-scoped is nil,
$tasksByResidence when set) with a single $allTasks observation
that filters in-memory when currentResidenceId is set.

Eliminates the gitea#2 race window where the per-residence cache slot
could be empty while $allTasks was populated, leaving residence
detail stuck on the empty state. After this commit, every emit of
_allTasks rerenders every observing view — kanban tab, residence
detail, dashboards — atomically.

Refs gitea#2

iosApp/iosApp/Task/TaskViewModel.swift

@@ -42,33 +42,24 @@ class TaskViewModel: ObservableObject {
 
     // MARK: - Initialization
     init() {
-        // Observe DataManagerObservable for all tasks data
+        // Single source of truth = DataManager._allTasks. When this VM is
+        // residence-scoped (currentResidenceId set), filter in-memory by
+        // residence id. Eliminates the gitea#2 race window where the
+        // per-residence cache slot could be empty while _allTasks was
+        // populated. Phase 3 deletes the per-residence cache entirely.
         DataManagerObservable.shared.$allTasks
             .receive(on: DispatchQueue.main)
             .sink { [weak self] allTasks in
-                // Skip DataManager updates during completion animation to prevent
-                // the task from being moved out of its column before the animation finishes
-                guard self?.isAnimatingCompletion != true else { return }
-                // Only update if we're showing all tasks (no residence filter)
-                if self?.currentResidenceId == nil {
-                    self?.tasksResponse = allTasks
-                    if allTasks != nil {
-                        self?.isLoadingTasks = false
-                    }
-                }
-            }
-            .store(in: &cancellables)
+                guard let self else { return }
+                guard !self.isAnimatingCompletion else { return }
 
-        // Observe tasks by residence
-        DataManagerObservable.shared.$tasksByResidence
-            .receive(on: DispatchQueue.main)
-            .sink { [weak self] tasksByResidence in
-                guard self?.isAnimatingCompletion != true else { return }
-                // Only update if we're filtering by residence
-                if let resId = self?.currentResidenceId,
-                   let tasks = tasksByResidence[resId] {
-                    self?.tasksResponse = tasks
-                    self?.isLoadingTasks = false
+                if let allTasks {
+                    if let resId = self.currentResidenceId {
+                        self.tasksResponse = self.filterTasks(allTasks, residenceId: resId)
+                    } else {
+                        self.tasksResponse = allTasks
+                    }
+                    self.isLoadingTasks = false
                 }
             }
             .store(in: &cancellables)
@@ -382,6 +373,28 @@ class TaskViewModel: ObservableObject {
         }
     }
 
+    /// Filter the all-tasks kanban down to a single residence in-memory.
+    /// Mirrors `DataManager.getTasksForResidence` on the Kotlin side.
+    private func filterTasks(_ response: TaskColumnsResponse, residenceId: Int32) -> TaskColumnsResponse {
+        let filteredColumns = response.columns.map { column -> TaskColumn in
+            let filteredTasks = column.tasks.filter { Int32($0.residenceId) == residenceId }
+            return TaskColumn(
+                name: column.name,
+                displayName: column.displayName,
+                buttonTypes: column.buttonTypes,
+                icons: column.icons,
+                color: column.color,
+                tasks: filteredTasks,
+                count: Int32(filteredTasks.count)
+            )
+        }
+        return TaskColumnsResponse(
+            columns: filteredColumns,
+            daysThreshold: response.daysThreshold,
+            residenceId: String(residenceId)
+        )
+    }
+
     /// Updates a task in the kanban board by moving it to the correct column based on kanban_column
     func updateTaskInKanban(_ updatedTask: TaskResponse) {
         guard let currentResponse = tasksResponse else { return }