fix: bulkCreateTasks force-refreshes _allTasks instead of merging task-by-task

Server is the authoritative kanban categorizer. After a bulk insert,
re-fetch /api/tasks/ so the kanban view reflects exactly what the
server sees, including any column re-categorizations the client's
in-memory upsert wouldn't compute. One extra round-trip per onboarding
submission, called once per session typically.

Eliminates the entire bug class where DataManager.updateTask had to
correctly compute kanban column placement from the response's
kanbanColumn field. With force-refresh, the server is the source of
truth — fewer ways for the client cache to drift.

Refs gitea#2

composeApp/src/commonMain/kotlin/com/tt/honeyDue/network/APILayer.kt

@@ -640,9 +640,15 @@ object APILayer {
 
     /**
      * Atomically creates 1-50 tasks via POST /api/tasks/bulk/. The whole
-     * batch succeeds or fails together on the server. On success, every
-     * returned task is merged into DataManager.allTasks so observing views
-     * render the new batch immediately.
+     * batch succeeds or fails together on the server. On success, force-
+     * refreshes _allTasks from the server — the server is the
+     * authoritative kanban categorizer, and a single round-trip
+     * eliminates any drift between the per-task `kanbanColumn` hint and
+     * the global kanban view.
+     *
+     * This is the bug-class fix for gitea#2: the previous per-task
+     * updateTask loop was a no-op when _allTasks was null (fresh launch
+     * after onboarding), silently dropping the new tasks from cache.
      */
     suspend fun bulkCreateTasks(request: BulkCreateTasksRequest): ApiResult<BulkCreateTasksResponse> {
         val token = getToken() ?: return ApiResult.Error("Not authenticated", 401)
@@ -650,7 +656,9 @@ object APILayer {
 
         if (result is ApiResult.Success) {
             DataManager.setTotalSummary(result.data.summary)
-            result.data.tasks.forEach { DataManager.updateTask(it) }
+            // Authoritative refresh — replaces any placeholder kanban
+            // shell from updateTask with proper server data.
+            getTasks(forceRefresh = true)
         }
         return result
     }