feat: add 'j' and 'k' as keybindings for navigation

[rtuszik]

adds j and k as up and down navigation keys in addition to arrow keys as commonly used with tui applications

[Adembc]

Thanks for the PR! 🙌 It looks great.
Just one small tweak, currently the up/down arrow keys wrap around when hitting the first/last server, so j and k should behave the same way.Fix this and I’ll merge it!

func (t *tui) handleNavigateDown() {
	if t.app.GetFocus() == t.serverList {
		currentIdx := t.serverList.GetCurrentItem()
		itemCount := t.serverList.GetItemCount()
		if currentIdx < itemCount-1 {
			t.serverList.SetCurrentItem(currentIdx + 1)
		} else {
			t.serverList.SetCurrentItem(0)
		}
	}
}

func (t *tui) handleNavigateUp() {
	if t.app.GetFocus() == t.serverList {
		currentIdx := t.serverList.GetCurrentItem()
		if currentIdx > 0 {
			t.serverList.SetCurrentItem(currentIdx - 1)
		} else {
			t.serverList.SetCurrentItem(t.serverList.GetItemCount() - 1)
		}
	}
}

[rtuszik]

Good point.
Added!