adds single-page-application dashboard

config.json

go.mod

go.sum

main.go

packages/gossip/manager.go

packages/netutil/buffconn/buffconn.go

packages/shutdown/order.go

plugins/gossip/gossip.go

plugins/spa/explorer_routes.go

plugins/spa/frontend/.gitignore

plugins/spa/frontend/.prettierrc

plugins/spa/frontend/README.md

plugins/spa/frontend/package.json

plugins/spa/frontend/src/app/App.tsx

plugins/spa/frontend/src/app/components/Dashboard.tsx

plugins/spa/frontend/src/app/components/Explorer.tsx

plugins/spa/frontend/src/app/components/Explorer404.tsx

...spa/frontend/src/app/components/ExplorerAddressResult.tsx

plugins/spa/frontend/src/app/components/ExplorerLiveFeed.tsx

...ins/spa/frontend/src/app/components/ExplorerSearchbar.tsx