Release 2.7.3.1: harden proxy recovery, updates and local API.

Restore orphaned system proxy after crash, require update SHA-256, add macOS /api auth token, fix UDP ping false positives, HTTPS-only subscriptions, and keep the UI responsive during connect.

Co-authored-by: Cursor <cursoragent@cursor.com>

cmd/vpnapp/main_darwin.go

@@ -58,10 +58,11 @@ func main() {
 		}()
 	}
 
-	ln, uiURL, err := apphost.ListenLocal()
+	ln, uiURL, token, err := apphost.ListenLocal()
 	if err != nil {
 		fatalf("listen: %v", err)
 	}
+	a.APIToken = token
 	srv := &http.Server{Handler: a.Handler()}
 	go func() {
 		_ = srv.Serve(ln)