feat: add api security foundation

Tiku.Api/Options/JwtOptions.cs

@@ -0,0 +1,19 @@
+using Microsoft.IdentityModel.Tokens;
+using System.Text;
+
+namespace Tiku.Api.Options;
+
+public sealed class JwtOptions
+{
+    public string Issuer { get; set; } = "tiku-backend";
+    public string Audience { get; set; } = "tiku-api";
+    public string SigningKey { get; set; } = "development-only-tiku-signing-key-change-before-production";
+    public int AccessTokenMinutes { get; set; } = 30;
+    public int RefreshTokenDays { get; set; } = 30;
+
+    public SymmetricSecurityKey CreateSecurityKey()
+    {
+        ArgumentException.ThrowIfNullOrWhiteSpace(SigningKey);
+        return new SymmetricSecurityKey(Encoding.UTF8.GetBytes(SigningKey));
+    }
+}