fix: SSO Auth CORS 정책 강화 및 Redis 세션 지원 추가

- CORS origin 검증 로직 추가 (운영 도메인 + localhost + 192.168.x.x)
- Redis 기반 세션/토큰 관리 유틸 추가
- departments 테이블 JOIN 지원 (findByUsername, findById)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

sso-auth-service/index.js

@@ -10,12 +10,25 @@
 const express = require('express');
 const cors = require('cors');
 const authRoutes = require('./routes/authRoutes');
+const { initRedis } = require('./utils/redis');
 
 const app = express();
 const PORT = process.env.PORT || 3000;
 
+const allowedOrigins = [
+  'https://tkfb.technicalkorea.net',
+  'https://tkreport.technicalkorea.net',
+  'https://tkqc.technicalkorea.net',
+  'https://tkuser.technicalkorea.net',
+];
+if (process.env.NODE_ENV === 'development') {
+  allowedOrigins.push('http://localhost:30000', 'http://localhost:30080', 'http://localhost:30180', 'http://localhost:30280', 'http://localhost:30380');
+}
 app.use(cors({
-  origin: true,
+  origin: function(origin, cb) {
+    if (!origin || allowedOrigins.includes(origin) || /^http:\/\/(192\.168\.\d+\.\d+|localhost)(:\d+)?$/.test(origin)) return cb(null, true);
+    cb(new Error('CORS blocked: ' + origin));
+  },
   credentials: true
 }));
 app.use(express.json());
@@ -42,7 +55,8 @@ app.use((err, req, res, next) => {
   });
 });
 
-app.listen(PORT, () => {
+app.listen(PORT, async () => {
+  await initRedis();
   console.log(`SSO Auth Service running on port ${PORT}`);
 });