feat: l goes to the details of what's selected; enter still drills in

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

internal/ui/app/app.go

@@ -821,6 +821,8 @@ func (m *Model) handleKey(msg tea.KeyPressMsg) (cmd tea.Cmd, quit bool) {
 		if r, ok := m.sources.Selected(); ok && m.focus == paneContainers && r.kind == rowGroup {
 			m.focus = paneDetail // an account's row: nothing between
 		}
+	case key.Matches(msg, k.Details):
+		m.focus = paneDetail // what's selected, on the right
 	case key.Matches(msg, k.PrevPane):
 		if m.focus == paneDetail {
 			m.focus = m.lastLeft // back to what it describes