feat: complete Phase 12 — voice playback ticker, cache, config, and UI

Add playback position ticker in event loop with 1s UI refresh rate,
integrate VoiceCache for downloaded voice files, add [audio] config
section (cache_size_mb, auto_download_voice), and render progress bar
with waveform visualization in message bubbles.

Fix race conditions in AudioPlayer: add `starting` flag to prevent
false `is_stopped()` during ffplay startup, guard pid cleanup so old
threads don't overwrite newer process pids. Implement `resume_from()`
with ffplay `-ss` for real audio seek on unpause (-1s rewind).

Kill ffplay on app exit via `stop_playback()` in shutdown + Drop impl.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/main.rs

@@ -167,6 +167,42 @@ async fn run_app<B: ratatui::backend::Backend, T: tdlib::TdClientTrait>(
             app.needs_redraw = true;
         }
 
+        // Обновляем позицию воспроизведения голосового сообщения
+        {
+            let mut stop_playback = false;
+            if let Some(ref mut playback) = app.playback_state {
+                use crate::tdlib::PlaybackStatus;
+                match playback.status {
+                    PlaybackStatus::Playing => {
+                        let prev_second = playback.position as u32;
+                        if let Some(last_tick) = app.last_playback_tick {
+                            let delta = last_tick.elapsed().as_secs_f32();
+                            playback.position += delta;
+                        }
+                        app.last_playback_tick = Some(std::time::Instant::now());
+
+                        // Проверяем завершение воспроизведения
+                        if playback.position >= playback.duration
+                            || app.audio_player.as_ref().map_or(false, |p| p.is_stopped())
+                        {
+                            stop_playback = true;
+                        }
+                        // Перерисовка только при смене секунды (не 60 FPS)
+                        if playback.position as u32 != prev_second || stop_playback {
+                            app.needs_redraw = true;
+                        }
+                    }
+                    _ => {
+                        app.last_playback_tick = None;
+                    }
+                }
+            }
+            if stop_playback {
+                app.stop_playback();
+                app.last_playback_tick = None;
+            }
+        }
+
         // Рендерим только если есть изменения
         if app.needs_redraw {
             terminal.draw(|f| ui::render(f, app))?;
@@ -185,6 +221,9 @@ async fn run_app<B: ratatui::backend::Backend, T: tdlib::TdClientTrait>(
                         // Graceful shutdown
                         should_stop.store(true, Ordering::Relaxed);
 
+                        // Останавливаем воспроизведение голосового (убиваем ffplay)
+                        app.stop_playback();
+
                         // Закрываем TDLib клиент
                         let _ = tdlib_rs::functions::close(app.td_client.client_id()).await;