[Feature Request] Add controller support to the web ui

Since [HTML5 Gamepad API](https://www.w3.org/TR/gamepad/) is widely adopted among modern browsers we should support it to enable the web app to be used inside the ChimeraOS device itself. That could enable us to migrate to a store-like UI for other platforms and maybe embed this app as a OS-manager accessible as a tool.

Here is the specification itself: https://www.w3.org/TR/gamepad/
A help from Mozilla: https://developer.mozilla.org/en-US/docs/Web/API/Gamepad_API
And a usage example: https://github.com/luser/gamepadtest

Start by reviewing the web UI entry points and the HTML5 Gamepad API specification and Mozilla guide linked in the issue. Use the gamepadtest example to understand browser input handling, then determine where controller actions belong in the existing interface. Done means the web app can be operated with a supported controller.

Written by the indexing model from the issue text.