feat: An Initias Redis Store Implementation

- **docker-compose.yml**
  - Added Redis service configuration to support token storage.
  - Set up health checks and volume for Redis persistence.
  - Configured VRCAuthProxy service to depend on Redis.

- **HttpClientCookieContainer.cs**
  - Added `Username` property to support user-specific token management.

- **Program.cs**
  - Integrated Redis for storing and retrieving authentication tokens.
  - Updated login and token rotation logic to utilize Redis.
  - Improved async/await usage for better reliability.

- **VRCAuthProxy.csproj**
  - Added `StackExchange.Redis` package for Redis connectivity.
  - Corrected `Otp.NET` package reference.

- **API.cs**
  - Updated `TotpVerifyResponse` and `User` classes to be nullable-aware.

- **RedisService.cs**
  - Implemented Redis service for managing authentication tokens.
  - Added methods for saving, retrieving, and deleting tokens.

VRCAuthProxy/types/API.cs

@@ -1,11 +1,13 @@
 namespace VRCAuthProxy.types;
 
-public struct TotpVerifyResponse
+public class TotpVerifyResponse
 {
     public bool verified { get; set; }
 }
 
-public struct User
+public class User
 {
-    public string displayName { get; set; }
+    public string? displayName { get; set; }
+    public bool? requiresTwoFactorAuth { get; set; }
+    public bool? totp { get; set; }
 }