Add Register and Forget actions to devices list

Adds a context menu to each device card with contextual actions:
- Unregistered devices show a Register option (dialog with owner field
  and device type dropdown)
- Registered devices show a Forget option (confirmation dialog)

Also fixes CORS to allow PUT and DELETE methods, adds device type
tooltips on the icon, and renames the "New" filter/badge to
"Not registered".

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/src/web_server.rs

@@ -80,6 +80,12 @@ pub async fn serve() -> Result<(), Box<dyn Error>> {
     // Allow all origins and headers for API
     let cors_layer = CorsLayer::new()
         .allow_origin(Any)
+        .allow_methods([
+            http::Method::GET,
+            http::Method::POST,
+            http::Method::PUT,
+            http::Method::DELETE,
+        ])
         .allow_headers([http::header::AUTHORIZATION, http::header::CONTENT_TYPE]);
 
     let router = Router::new()