feat: integrate Kakao OAuth for user authentication and enhance user repository

- Added Kakao OAuth client implementation for handling authentication flows.
- Updated user repository to support OAuth-based user creation and retrieval.
- Introduced Redis-based session management for OAuth sessions.
- Enhanced in-memory user repository to handle OAuth user data.
- Updated environment configuration files to include new OAuth settings.
- Modified API routes to support Kakao login and registration flows.
- Added Prisma schema updates for user model to accommodate OAuth fields.
- Implemented tests for the new authentication flow and user repository methods.

app/gateway-api/test/authFlow.test.ts

@@ -2,6 +2,7 @@ import { describe, expect, it } from 'vitest';
 
 import { InMemoryGatewaySessionService } from '../src/auth/inMemorySessionService.js';
 import { createInMemoryUserRepository } from '../src/auth/inMemoryUserRepository.js';
+import { InMemoryOAuthSessionStore } from '../src/auth/oauthSessionStore.js';
 import { createGatewayApiContext } from '../src/context.js';
 import { appRouter } from '../src/router.js';
 
@@ -14,21 +15,57 @@ const buildCaller = () => {
     const flushPublisher = {
         publishUserFlush: async () => {},
     };
-    return appRouter.createCaller(
+    const oauthSessions = new InMemoryOAuthSessionStore();
+    const kakaoClient = {
+        buildAuthUrl: () => '',
+        exchangeCode: async () => {
+            throw new Error('not used');
+        },
+        refreshToken: async () => {
+            throw new Error('not used');
+        },
+        signup: async () => ({ id: '1' }),
+        getMe: async () => ({
+            id: '1',
+            kakaoAccount: {
+                hasEmail: true,
+                email: 'tester@example.com',
+                isEmailValid: true,
+                isEmailVerified: true,
+            },
+        }),
+        sendTalkMessage: async () => {},
+    };
+    const caller = appRouter.createCaller(
         createGatewayApiContext({
             users,
             sessions,
             flushPublisher,
             gameTokenSecret: 'test-secret',
             gameSessionTtlSeconds: 600,
+            kakaoClient,
+            oauthSessions,
+            publicBaseUrl: 'http://localhost',
         })
     );
+    return { caller, oauthSessions };
 };
 
 describe('gateway auth flow', () => {
     it('registers and issues a game session', async () => {
-        const caller = buildCaller();
+        const { caller, oauthSessions } = buildCaller();
+        const oauthSession = await oauthSessions.createSession({
+            mode: 'login',
+            kakaoId: '1',
+            email: 'tester@example.com',
+            accessToken: 'token',
+            refreshToken: 'refresh',
+            accessTokenValidUntil: new Date().toISOString(),
+            refreshTokenValidUntil: new Date().toISOString(),
+            createdAt: new Date().toISOString(),
+        });
         const register = await caller.auth.register({
+            oauthSessionId: oauthSession.id,
             username: 'tester',
             password: 'secretpass',
             displayName: 'Tester',