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/shared/database/drizzle.ts

@@ -0,0 +1,129 @@
+import { drizzle as drizzlePostgres } from "drizzle-orm/node-postgres";
+import type { PoolClient } from "pg";
+import { Pool } from "pg";
+import { config } from "../../shared/config/config.js";
+import { createChildLogger } from "../../shared/logger/logger.js";
+import * as schema from "./schema.js";
+
+const logger = createChildLogger("drizzle");
+
+let db: ReturnType<typeof drizzlePostgres> | null = null;
+let rawPool: Pool | null = null;
+
+/**
+ * Initialize the PostgreSQL database connection.
+ */
+export async function initializeDatabase() {
+  if (db !== null) {
+    return db;
+  }
+
+  let pool: Pool;
+
+  if (config.DATABASE_URL) {
+    pool = new Pool({
+      connectionString: config.DATABASE_URL,
+      min: config.POSTGRES_POOL_MIN,
+      max: config.POSTGRES_POOL_MAX,
+    });
+  } else {
+    pool = new Pool({
+      host: config.POSTGRES_HOST,
+      port: config.POSTGRES_PORT,
+      user: config.POSTGRES_USER,
+      password: config.POSTGRES_PASSWORD,
+      database: config.POSTGRES_DB,
+      min: config.POSTGRES_POOL_MIN,
+      max: config.POSTGRES_POOL_MAX,
+    });
+  }
+
+  rawPool = pool;
+  db = drizzlePostgres(pool, { schema });
+
+  try {
+    (db as { run?: (sql: string) => Promise<unknown> }).run = (sql: string) =>
+      pool.query(sql);
+  } catch {
+    // ignore
+  }
+
+  logger.info("PostgreSQL database initialized");
+  return db;
+}
+
+/**
+ * Get the initialized database instance.
+ * Throws if database has not been initialized.
+ */
+export function getDatabase() {
+  if (db === null) {
+    throw new Error(
+      "Database not initialized. Call initializeDatabase() first.",
+    );
+  }
+  return db;
+}
+
+function convertPlaceholdersForPostgres(sql: string) {
+  let i = 0;
+  return sql.replace(/\?/g, () => `$${++i}`);
+}
+
+export async function executeAll(sql: string, params?: unknown[]) {
+  if (!rawPool) {
+    throw new Error(
+      "Database not initialized. Call initializeDatabase() first.",
+    );
+  }
+
+  const query = convertPlaceholdersForPostgres(sql);
+  const result = await rawPool.query(query, params || []);
+  return result.rows;
+}
+
+export async function executeGet(sql: string, params?: unknown[]) {
+  if (!rawPool) {
+    throw new Error(
+      "Database not initialized. Call initializeDatabase() first.",
+    );
+  }
+
+  const query = convertPlaceholdersForPostgres(sql);
+  const result = await rawPool.query(query, params || []);
+  return result.rows[0] ?? null;
+}
+
+/**
+ * Run a function with a dedicated PostgreSQL client from the shared pool.
+ * Use this for session-scoped operations such as advisory locks.
+ */
+export async function withDatabaseClient<T>(
+  callback: (client: PoolClient) => Promise<T>,
+): Promise<T> {
+  if (!rawPool) {
+    throw new Error(
+      "Database not initialized. Call initializeDatabase() first.",
+    );
+  }
+
+  const client = await rawPool.connect();
+  try {
+    return await callback(client);
+  } finally {
+    client.release();
+  }
+}
+
+/**
+ * Close the PostgreSQL connection pool.
+ */
+export async function closeDatabase() {
+  if (rawPool !== null) {
+    await rawPool.end();
+  }
+
+  rawPool = null;
+  db = null;
+  logger.info("PostgreSQL database closed");
+}