improvement: InMemoryTokenStore를 Redis 기반으로 교체 (#162)

Reviewed-on: https://git.ipstein.myds.me/SPMS/SPMS_API/pulls/163

SPMS.Infrastructure/Caching/RedisTokenStore.cs

@@ -0,0 +1,68 @@
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Options;
+using SPMS.Application.Interfaces;
+using SPMS.Application.Settings;
+
+namespace SPMS.Infrastructure.Caching;
+
+public class RedisTokenStore : ITokenStore
+{
+    private readonly RedisConnection _redis;
+    private readonly RedisSettings _settings;
+    private readonly ILogger<RedisTokenStore> _logger;
+
+    public RedisTokenStore(
+        RedisConnection redis,
+        IOptions<RedisSettings> settings,
+        ILogger<RedisTokenStore> logger)
+    {
+        _redis = redis;
+        _settings = settings.Value;
+        _logger = logger;
+    }
+
+    public async Task StoreAsync(string key, string value, TimeSpan expiry)
+    {
+        try
+        {
+            var db = await _redis.GetDatabaseAsync();
+            await db.StringSetAsync(BuildKey(key), value, expiry);
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "토큰 저장 실패: key={Key}", key);
+            throw;
+        }
+    }
+
+    public async Task<string?> GetAsync(string key)
+    {
+        try
+        {
+            var db = await _redis.GetDatabaseAsync();
+            var value = await db.StringGetAsync(BuildKey(key));
+            return value.IsNullOrEmpty ? null : value.ToString();
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "토큰 조회 실패: key={Key}", key);
+            throw;
+        }
+    }
+
+    public async Task RemoveAsync(string key)
+    {
+        try
+        {
+            var db = await _redis.GetDatabaseAsync();
+            await db.KeyDeleteAsync(BuildKey(key));
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "토큰 삭제 실패: key={Key}", key);
+            throw;
+        }
+    }
+
+    private string BuildKey(string key) => $"{_settings.InstanceName}token:{key}";
+}

SPMS.Infrastructure/DependencyInjection.cs

@@ -88,8 +88,7 @@ public static class DependencyInjection
         services.AddHostedService<DataRetentionWorker>();
 
         // Token Store & Email Service
-        services.AddMemoryCache();
-        services.AddSingleton<ITokenStore, InMemoryTokenStore>();
+        services.AddSingleton<ITokenStore, RedisTokenStore>();
         services.AddSingleton<IEmailService, ConsoleEmailService>();
 
         return services;