feat(modules): 帮助中心、工单、工作流与多渠道接入

补齐 FAQ、帮助中心、工单、可视化工作流及 Telegram/WhatsApp/Slack 等渠道模块。

backend/app/channels/__init__.py

@@ -0,0 +1,30 @@
+"""
+Copyright 2024-2026 ChatterMate
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+"""
+
+from app.channels.base import (
+    ChannelAdapter, InboundMessage, SendResult, WindowStatus, ChannelInteraction,
+)
+from app.channels.registry import get_adapter, register_adapter
+
+__all__ = [
+    "ChannelAdapter",
+    "InboundMessage",
+    "SendResult",
+    "WindowStatus",
+    "ChannelInteraction",
+    "get_adapter",
+    "register_adapter",
+]