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/backend/src/modules/messages/messages.controller.ts

@@ -0,0 +1,74 @@
+import type { NextFunction, Request, Response } from "express";
+import { createChildLogger } from "../../shared/logger/index.js";
+import { asyncHandler } from "../../shared/middlewares/index.js";
+import { messageQuerySchema } from "./messages.schema.js";
+import { messagesService } from "./messages.service.js";
+
+const logger = createChildLogger("messages.controller");
+
+function requireRouteParam(
+  value: string | string[] | undefined,
+  name: string,
+): string {
+  if (typeof value !== "string" || value.length === 0) {
+    throw new Error(`Missing route parameter: ${name}`);
+  }
+  return value;
+}
+
+export function handleListMessages(
+  req: Request,
+  res: Response,
+  next: NextFunction,
+) {
+  return asyncHandler(async (req: Request, res: Response) => {
+    const query = messageQuerySchema.parse(req.query);
+    logger.debug({ query }, "Handling list messages request");
+    const result = await messagesService.listMessages(query);
+    res.json(result);
+  })(req, res, next);
+}
+
+export function handleGetMessagesByChannel(
+  req: Request,
+  res: Response,
+  next: NextFunction,
+) {
+  return asyncHandler(async (req: Request, res: Response) => {
+    const channelId = requireRouteParam(req.params.channelId, "channelId");
+    const query = messageQuerySchema.parse(req.query);
+    logger.debug({ channelId, query }, "Handling get messages by channel");
+    const result = await messagesService.getMessagesByChannel(channelId, query);
+    res.json(result);
+  })(req, res, next);
+}
+
+export function handleGetMessageById(
+  req: Request,
+  res: Response,
+  next: NextFunction,
+) {
+  return asyncHandler(async (req: Request, res: Response) => {
+    const id = requireRouteParam(req.params.id, "id");
+    logger.debug({ id }, "Handling get message by ID");
+    const result = await messagesService.getMessageById(id);
+    res.json(result);
+  })(req, res, next);
+}
+
+export function handleGetAttachmentsByChannel(
+  req: Request,
+  res: Response,
+  next: NextFunction,
+) {
+  return asyncHandler(async (req: Request, res: Response) => {
+    const channelId = requireRouteParam(req.params.channelId, "channelId");
+    const query = messageQuerySchema.parse(req.query);
+    logger.debug({ channelId, query }, "Handling get attachments by channel");
+    const result = await messagesService.getAttachmentsByChannel(
+      channelId,
+      query,
+    );
+    res.json(result);
+  })(req, res, next);
+}