H-337: restore Web widget reply visibility (#64)

* H-337: restore widget reply delivery

* H-337: harden widget conversation ownership

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Co-authored-by: Rogee <rogee@ipao.vip>

backend/internal/handler/ws/hub_extra_test.go

@@ -61,8 +61,8 @@ func TestHub_Register_ContactWithPresence(t *testing.T) {
 
 	hub.Register(client)
 	assert.Contains(t, hub.clients, client.ID)
-	// Contact should be auto-subscribed to account room + pubsub_token room
-	assert.True(t, client.SubscribedRooms[accountRoomName(10)])
+	// Contacts only receive events addressed to their own pubsub token.
+	assert.False(t, client.SubscribedRooms[accountRoomName(10)])
 	assert.True(t, client.SubscribedRooms[pubsubTokenRoomName("token123")])
 
 	hub.Unregister(client)