refactor: eliminate code duplication - extract helpers and use retry utils

Extracted duplicate code and unified timeout handling across the codebase.

Changes:
- Extracted open_chat_and_load_data() function (eliminates 52 lines of duplication)
- Replaced manual y/н/Enter handling with handle_yes_no() from modal_handler (2 places)
- Replaced 7 direct tokio::time::timeout calls with retry utils (auth, main_input, main)
- Added with_timeout_ignore() for non-critical operations
- Fixed modal_handler.rs bug: corrected Russian 'y' key (д → н)
- Removed unused imports in handlers/mod.rs and utils/mod.rs

Impact:
- main_input.rs: 1164 → 958 lines (-206 lines, -18%)
- Code duplication: 52 lines eliminated
- Direct timeout calls: 7 → 1 (-86%)
- DRY principle applied throughout

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/main.rs

@@ -205,7 +205,7 @@ async fn run_app<B: ratatui::backend::Backend, T: tdlib::TdClientTrait>(
 
 /// Возвращает true если состояние изменилось и требуется перерисовка
 async fn update_screen_state<T: tdlib::TdClientTrait>(app: &mut App<T>) -> bool {
-    use tokio::time::timeout;
+    use utils::with_timeout_ignore;
 
     let prev_screen = app.screen.clone();
     let prev_status = app.status_message.clone();
@@ -227,8 +227,8 @@ async fn update_screen_state<T: tdlib::TdClientTrait>(app: &mut App<T>) -> bool
                 app.is_loading = true;
                 app.status_message = Some("Загрузка чатов...".to_string());
 
-                // Запрашиваем загрузку чатов с таймаутом
-                let _ = timeout(Duration::from_secs(5), app.td_client.load_chats(50)).await;
+                // Запрашиваем загрузку чатов с таймаутом (игнорируем ошибки)
+                with_timeout_ignore(Duration::from_secs(5), app.td_client.load_chats(50)).await;
             }
 
             // Синхронизируем чаты из td_client в app