feat: add /announcement owner-only slash command

Triggers a modal with a content text input and category select menu,
calls the announcement API, DMs generated copy as file attachments,
and replies ephemerally with the platform recap.

bot/src/index.ts

@@ -7,6 +7,9 @@
 import { DiscordAnalytics } from "@nhcarrigan/discord-analytics";
 import { Client, Events, GatewayIntentBits, Partials } from "discord.js";
 import { chatInputInteractionCreate } from "./events/interactionCreate.js";
+import {
+  modalSubmitInteractionCreate,
+} from "./events/modalInteractionCreate.js";
 import { logger } from "./utils/logger.js";
 
 /*
@@ -51,6 +54,10 @@ hikari.once(Events.ClientReady, () => {
 hikari.on(Events.InteractionCreate, (interaction) => {
   if (interaction.isChatInputCommand()) {
     void chatInputInteractionCreate(hikari, interaction);
+    return;
+  }
+  if (interaction.isModalSubmit()) {
+    void modalSubmitInteractionCreate(hikari, interaction);
   }
 });