feat: implement header component for improved branding in TUI

[Soner (shyim)]

Move header into own component for easier adding things

[Soner (shyim)]

Anne (@Ant1gua) the idea here would be now to accept an ctx and do something like this

type LatestVersionMsg struct{ Version string }

func NewHeader(ctx ) Header {
  h := Header{}
  h.fetchLatest = func() tea.Msg {
        ctx, cancel := context.WithTimeout(ctx, time.Second)
        defer cancel()

        latest, err := fetchLatestRelease(ctx)
        if err != nil {
            return nil
        }
        return LatestVersionMsg{Version: latest}
    }
}

func (h Header) Init() tea.Cmd {
    return h.fetchLatest
}

func (h Header) Update(msg tea.Msg) (Header, tea.Cmd) {
    if msg, ok := msg.(LatestVersionMsg); ok && newerThanApp(msg.Version) {
        // Adjust h to add the latest version
    }
    return h, nil
}