refactor(gateway): 拆 ws_hub.go 589→182(纯搬移零逻辑) — conn/turn/origin/message_event 四文件

- ws_hub.go 182(hub核心/常量/wsEvent/newHub/broadcast) + ws_hub_conn.go 165(连接层handleWS/read·writePump) + ws_hub_turn.go 168(relay/streamChat/runTurn/interrupt/broadcastStream) + ws_hub_origin.go 73(Origin校验) + ws_hub_message_event.go 30(message_edited/deleted广播)
- 代码行多重集 identical + 顶层声明diff空; 每文件≤500/函数≤80(最大handleWS 28/streamChat 25)
- gateway测试绿 + build/vet + win/darwin交叉编译绿

internal/services/gateway/ws_hub_message_event.go

@@ -0,0 +1,30 @@
+package gateway
+
+// wsMessageEdited / wsMessageDeleted are the downstream event types of the D3
+// history writes: a message's content was edited, or a message was removed. Both
+// reuse the wsEvent envelope and the same all-connections fan-out as
+// `message_persisted` — the hub has no per-session subscription, so the frame
+// carries SessionID and a client filters it by its active session, exactly as it
+// does for message_persisted.
+const (
+	wsMessageEdited  = "message_edited"
+	wsMessageDeleted = "message_deleted"
+)
+
+// broadcastMessageEdited fans a content edit out to every client as a
+// `message_edited` frame whose data is the updated message DTO. The frame is a
+// render-only sync: the edited content's single source of truth stays the history
+// store, so a client that missed the frame converges again on its next read. The
+// caller strips Thinking to match the message_persisted/replay contract.
+func (h *hub) broadcastMessageEdited(msg historyMessage) {
+	h.broadcast(wsEvent{Type: wsMessageEdited, SessionID: msg.SessionID, Data: msg})
+}
+
+// broadcastMessageDeleted fans a removal out to every client as a
+// `message_deleted` frame carrying the removed id (plus the owning sessionId for
+// client-side session filtering), so every browser of the account drops the row
+// without a refresh. sessionID may be empty when the store could not report it;
+// clients then fall back to the globally unique id.
+func (h *hub) broadcastMessageDeleted(sessionID, id string) {
+	h.broadcast(wsEvent{Type: wsMessageDeleted, SessionID: sessionID, Data: map[string]any{"id": id}})
+}