Add user authentication and account management system

Features:
- User registration with username, email, password
- Login with JWT token authentication
- Password hashing with BCrypt
- Account settings & management
- Device linking to accounts
- Change password & password reset
- Account-User relationship (1-to-1 with game data)

Database entities:
- Account: User accounts with credentials
- DeviceAccount: Link devices to accounts (many-to-many)

API endpoints:
- POST /api/auth/register
- POST /api/auth/login
- POST /api/auth/change-password
- POST /api/auth/forgot-password
- POST /api/auth/reset-password
- GET /api/auth/me
- POST /api/auth/link-device
- DELETE /api/auth/unlink-device/{deviceId}

Starting resources for new accounts:
- 100,000 Gold
- 500,000 Cash
- Level 1

Ready for VPS deployment with HTTPS.

RR3CommunityServer/RR3CommunityServer.csproj

@@ -16,6 +16,9 @@
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
       <PrivateAssets>all</PrivateAssets>
     </PackageReference>
+    <PackageReference Include="BCrypt.Net-Next" Version="4.0.3" />
+    <PackageReference Include="System.IdentityModel.Tokens.Jwt" Version="8.2.1" />
+    <PackageReference Include="Microsoft.AspNetCore.Authentication.JwtBearer" Version="8.0.11" />
   </ItemGroup>
 
 </Project>