fix: DataManager.updateTask seeds _allTasks when cache is empty (gitea#2)

Closes the silent no-op when _allTasks is null on first launch (the
onboarding bulkCreateTasks path). The function now upserts: builds an
empty kanban shell with the standard column names if needed and places
the task in its target column. Unknown column names append a new
column at the end so the task is always reachable.

Also drops the second branch that conditionally wrote to
_tasksByResidence — that cache is being deleted in Phase 3 and
updateTask should not maintain it any more.

The Phase 1 unit tests now pass; the Phase 2 force-refresh in the
next commit replaces the placeholder column metadata (display names,
colors, icons) with authoritative server values.

composeApp/src/commonMain/kotlin/com/tt/honeyDue/data/DataManager.kt

@@ -504,45 +504,60 @@ object DataManager : IDataManager {
      * Also refreshes the summary from the updated kanban data.
      */
     fun updateTask(task: TaskResponse) {
-        // Update in allTasks
-        _allTasks.value?.let { current ->
-            val targetColumn = task.kanbanColumn ?: "upcoming_tasks"
-            val newColumns = current.columns.map { column ->
-                // Remove task from this column if present
-                val filteredTasks = column.tasks.filter { it.id != task.id }
-                // Add task if this is the target column
-                val updatedTasks = if (column.name == targetColumn) {
-                    filteredTasks + task
-                } else {
-                    filteredTasks
-                }
-                column.copy(tasks = updatedTasks, count = updatedTasks.size)
-            }
-            _allTasks.value = current.copy(columns = newColumns)
-        }
+        val targetColumn = task.kanbanColumn ?: "upcoming_tasks"
 
-        // Update in tasksByResidence if this task's residence is cached
-        task.residenceId?.let { residenceId ->
-            _tasksByResidence.value[residenceId]?.let { current ->
-                val targetColumn = task.kanbanColumn ?: "upcoming_tasks"
-                val newColumns = current.columns.map { column ->
-                    val filteredTasks = column.tasks.filter { it.id != task.id }
-                    val updatedTasks = if (column.name == targetColumn) {
-                        filteredTasks + task
-                    } else {
-                        filteredTasks
-                    }
-                    column.copy(tasks = updatedTasks, count = updatedTasks.size)
-                }
-                _tasksByResidence.value = _tasksByResidence.value + (residenceId to current.copy(columns = newColumns))
-            }
+        // Upsert into _allTasks. Crucially, when _allTasks is null (fresh
+        // launch, kanban never fetched — the gitea#2 bug scenario), seed
+        // an empty kanban shell so the new task isn't silently dropped.
+        // The Phase 2 force-refresh after bulkCreateTasks/createTask will
+        // replace this shell with authoritative server data shortly.
+        val current = _allTasks.value ?: emptyKanbanShell()
+        val columnsWithTarget = if (current.columns.any { it.name == targetColumn }) {
+            current.columns
+        } else {
+            // Server returned a kanban_column the client doesn't know about
+            // yet — append it so the task is still reachable.
+            current.columns + emptyColumn(targetColumn)
         }
+        val newColumns = columnsWithTarget.map { column ->
+            val filteredTasks = column.tasks.filter { it.id != task.id }
+            val updatedTasks = if (column.name == targetColumn) filteredTasks + task else filteredTasks
+            column.copy(tasks = updatedTasks, count = updatedTasks.size)
+        }
+        _allTasks.value = current.copy(columns = newColumns)
 
         // Refresh summary from updated kanban data (API no longer returns summaries for CRUD)
         refreshSummaryFromKanban()
         persistToDisk()
     }
 
+    /// Default kanban skeleton used when `_allTasks` was never populated.
+    /// Display metadata is intentionally placeholder — the Phase 2 force-refresh
+    /// in `APILayer.bulkCreateTasks` / `createTask` replaces these shortly with
+    /// authoritative server values. The `name` field is the contract — every
+    /// observer keys off it.
+    private fun emptyKanbanShell(): TaskColumnsResponse = TaskColumnsResponse(
+        columns = listOf(
+            emptyColumn("overdue_tasks"),
+            emptyColumn("due_soon_tasks"),
+            emptyColumn("in_progress_tasks"),
+            emptyColumn("upcoming_tasks"),
+            emptyColumn("completed_tasks")
+        ),
+        daysThreshold = 30,
+        residenceId = ""
+    )
+
+    private fun emptyColumn(name: String): TaskColumn = TaskColumn(
+        name = name,
+        displayName = "",
+        buttonTypes = emptyList(),
+        icons = emptyMap(),
+        color = "",
+        tasks = emptyList(),
+        count = 0
+    )
+
     fun removeTask(taskId: Int) {
         // Remove from allTasks
         _allTasks.value?.let { current ->