feat(08-02): add smartDeleteTask to TaskActions provider

- Checks completion count before deleting
- Hard-deletes tasks with 0 completions
- Soft-deletes (isActive=false) tasks with completions
- Keeps existing deleteTask method for cascade/other uses

lib/features/tasks/presentation/task_providers.dart

@@ -89,4 +89,15 @@ class TaskActions extends _$TaskActions {
     final db = ref.read(appDatabaseProvider);
     await db.tasksDao.completeTask(taskId);
   }
+
+  /// Smart delete: hard-deletes tasks with no completions, soft-deletes tasks with completions.
+  Future<void> smartDeleteTask(int taskId) async {
+    final db = ref.read(appDatabaseProvider);
+    final completionCount = await db.tasksDao.getCompletionCount(taskId);
+    if (completionCount == 0) {
+      await db.tasksDao.deleteTask(taskId);
+    } else {
+      await db.tasksDao.softDeleteTask(taskId);
+    }
+  }
 }