added admin login to frontend + obscurification for contact details

backend/src/error.rs

@@ -11,6 +11,7 @@ pub enum AppError {
     Unauthorized,
     NotFound(String),
     BadRequest(String),
+    TooManyRequests(String),
     /// (public_message, internal_details) — details are logged but not returned.
     Internal(String, Option<String>),
 }
@@ -21,6 +22,7 @@ impl IntoResponse for AppError {
             AppError::Unauthorized => (StatusCode::UNAUTHORIZED, "Unauthorized".to_string()),
             AppError::NotFound(msg) => (StatusCode::NOT_FOUND, msg),
             AppError::BadRequest(msg) => (StatusCode::BAD_REQUEST, msg),
+            AppError::TooManyRequests(msg) => (StatusCode::TOO_MANY_REQUESTS, msg),
             AppError::Internal(msg, details) => {
                 if let Some(d) = details {
                     error!("Internal error: {} — {}", msg, d);