refactor: split app.py into mixins package

py_src/taskito/mixins/__init__.py

@@ -0,0 +1,19 @@
+"""Mixin classes that compose into the main Queue class."""
+
+from taskito.mixins.decorators import QueueDecoratorMixin
+from taskito.mixins.events import QueueEventsMixin
+from taskito.mixins.inspection import QueueInspectionMixin
+from taskito.mixins.lifecycle import QueueLifecycleMixin
+from taskito.mixins.locks import QueueLockMixin
+from taskito.mixins.operations import QueueOperationsMixin
+from taskito.mixins.resources import QueueResourceMixin
+
+__all__ = [
+    "QueueDecoratorMixin",
+    "QueueEventsMixin",
+    "QueueInspectionMixin",
+    "QueueLifecycleMixin",
+    "QueueLockMixin",
+    "QueueOperationsMixin",
+    "QueueResourceMixin",
+]

py_src/taskito/mixins/_shared.py

@@ -0,0 +1,6 @@
+"""Shared sentinels and helpers for Queue mixins."""
+
+from __future__ import annotations
+
+_UNSET = object()
+"""Sentinel to distinguish 'not passed' from explicit None in mixin defaults."""