Take a deleted bot out of the rail at once

Deleting a bot only changed the page after a reload. The delete route now
reads who could see the bot before removing it, since its assignments and
workspace places go with it, then pushes server:bot-removed
(BotRemovedData) to them. useLiveBots drops the row, so every tab and
every workspace the bot was in updates together.

src/bots-queue/push-bot-removed.ts

@@ -0,0 +1,28 @@
+import { sendToUser } from "@/src/websocket/(functions)/send-to-user";
+
+type Params = {
+    bot_id: number | string;
+    /**
+     * Everyone who saw the bot, read before its row was deleted: afterwards
+     * its assignments and workspace places are gone with it, so its
+     * audience can't be worked out any more.
+     */
+    user_ids: number[];
+};
+
+/**
+ * Pushes `server:bot-removed` to everyone who could see a bot that was
+ * deleted, so its rail row goes at once and nothing opens a dead
+ * conversation.
+ */
+export default function pushBotRemoved({ bot_id, user_ids }: Params) {
+    for (const user_id of user_ids) {
+        sendToUser({
+            user_id,
+            data: {
+                event: "server:bot-removed",
+                data: { bot_id: Number(bot_id) },
+            },
+        });
+    }
+}