refactor: split monolith into 3 microservices (frontend, backend, discord-gateway)

- Extract services into services/{frontend,backend,discord-gateway}
- Create packages/shared/ for shared logger, errors, utils, types
- Setup Modular MVC pattern in backend (controller→service→repository)
- Setup event-driven architecture in discord-gateway with Redis pub/sub
- Move Docker files to infra/docker/ with per-service Dockerfiles
- Update docker-compose.yml to use Traefik-only routing (no port exposes)
- Update GitHub Actions deploy workflow for multi-service matrix build
- Fix all import paths and resolve type errors across all services
- All 3 services pass tsc --noEmit clean

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

services/discord-gateway/src/app/shutdown.ts

@@ -0,0 +1,55 @@
+import type { Client } from "discord.js-selfbot-v13";
+import type { EventBroadcaster } from "../modules/event-broadcaster/index.js";
+import type { VoiceController } from "../modules/voice-recording/voiceController.js";
+import type { closeDatabase } from "../shared/database/drizzle.js";
+import type { createChildLogger } from "../shared/logger/logger.js";
+
+type Logger = ReturnType<typeof createChildLogger>;
+type CloseDatabase = typeof closeDatabase;
+
+export interface GracefulShutdownOptions {
+  logger: Logger;
+  closeDatabase: CloseDatabase;
+  voiceController: VoiceController;
+  client: Client;
+  eventBroadcaster: EventBroadcaster;
+}
+
+export function createGracefulShutdown(options: GracefulShutdownOptions) {
+  let isShuttingDown = false;
+
+  return async function gracefulShutdown(signal: string) {
+    if (isShuttingDown) {
+      options.logger.warn(`Already shutting down, ignoring ${signal}`);
+      return;
+    }
+
+    isShuttingDown = true;
+    options.logger.info({ signal }, "Graceful shutdown initiated");
+
+    try {
+      options.logger.info("Closing database...");
+      await options.closeDatabase();
+      options.logger.info("Database closed");
+
+      options.logger.info("Stopping voice connection...");
+      await options.voiceController.disconnect();
+
+      options.logger.info("Closing event broadcaster...");
+      await options.eventBroadcaster.close();
+
+      options.logger.info("Destroying Discord client...");
+      try {
+        options.client.destroy();
+      } catch (err) {
+        options.logger.warn({ error: err }, "Error destroying client");
+      }
+
+      options.logger.info("Graceful shutdown completed");
+      process.exit(0);
+    } catch (err) {
+      options.logger.error({ error: err }, "Error during graceful shutdown");
+      process.exit(1);
+    }
+  };
+}