refactor: switch webchat from sse to websocket (#1808)

* refactor: switch webchat from sse to websocket

* perf: image preview dialog

* chore: remove console.log

src/langbot/pkg/platform/sources/websocket.yaml

@@ -0,0 +1,17 @@
+apiVersion: v1
+kind: MessagePlatformAdapter
+metadata:
+  name: websocket
+  label:
+    en_US: "WebSocket Chat"
+    zh_Hans: "WebSocket 聊天"
+  description:
+    en_US: "WebSocket adapter for bidirectional real-time communication"
+    zh_Hans: "用于双向实时通信的 WebSocket 适配器"
+  icon: ""
+spec:
+  config: []
+execution:
+  python:
+    path: "websocket_adapter.py"
+    attr: "WebSocketAdapter"