fix(tui): surface late clarifications and stop bg bleed on input + action rows

- clarDismissed was model-global but only reset when the clarification's
  session was selected on arrival, so a clarification for an unselected
  session stayed silently hidden. Reset on every arrival.
- input bar (in-session + launcher) only truncated lines, never padded to
  width, so the terminal backdrop bled through the right. Pad with padTo.
- action/narration/user rows prefixed plain (unstyled) spacers around their
  icons, leaving transparent gaps near the symbols. Use bg-styled spacers.

apps/tui-go/internal/app/server.go

@@ -544,6 +544,10 @@ func (m *Model) onClarificationRequired(msg protocol.ServerMessage) {
 	if s := m.session(msg.SessionID); s != nil {
 		s.Clar = c
 	}
+	// A newly-arrived clarification must always surface. clarDismissed is model-global, and
+	// clarInitState (which clears it) only runs for the selected session — so a clarification
+	// arriving for an unselected session while the flag was left set would stay silently hidden.
+	m.clarDismissed = false
 	if msg.SessionID == m.selectedID {
 		m.clarInitState(len(qs))
 	}