feat: add local authentication

Tiku.Application/Auth/AuthExceptions.cs

@@ -0,0 +1,18 @@
+namespace Tiku.Application.Auth;
+
+public class AuthException(string code, string message) : Exception(message)
+{
+    public string Code { get; } = code;
+}
+
+public sealed class InvalidCredentialsException(string code = "invalid_credentials")
+    : AuthException(code, "The supplied credentials are invalid.");
+
+public sealed class TenantAccessDeniedException()
+    : AuthException("tenant_access_denied", "The user is not an active member of the requested tenant.");
+
+public sealed class SessionRevokedException()
+    : AuthException("session_revoked", "The session has been revoked or expired.");
+
+public sealed class SmsRateLimitedException()
+    : AuthException("sms_rate_limited", "SMS verification requests are rate limited.");