refactor: split app/mod.rs into trait-based architecture (1015→371 lines)

Split monolithic App impl into 5 specialized trait modules:
- methods/navigation.rs (NavigationMethods) - 7 methods for chat navigation
- methods/messages.rs (MessageMethods) - 8 methods for message operations
- methods/compose.rs (ComposeMethods) - 10 methods for reply/forward/draft
- methods/search.rs (SearchMethods) - 15 methods for search functionality
- methods/modal.rs (ModalMethods) - 27 methods for modal dialogs

Changes:
- app/mod.rs: 1015→371 lines (removed 644 lines, -63%)
- Created app/methods/ with 5 trait impl blocks
- Left in app/mod.rs: constructors, get_command, get_selected_chat_id/chat, getters/setters
- 116 functions → 5 trait impl blocks (67 in traits + 48 in core)
- Single Responsibility Principle achieved
- Updated CONTEXT.md with refactoring metrics
- Updated ROADMAP.md: Phase 13 Etap 2 marked as DONE

Phase 13 Etap 2: COMPLETED (100%)

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

src/app/methods/messages.rs

@@ -0,0 +1,125 @@
+//! Message methods for App
+//!
+//! Handles message selection, editing, and operations
+
+use crate::app::{App, ChatState};
+use crate::tdlib::{MessageInfo, TdClientTrait};
+
+/// Message operation methods
+pub trait MessageMethods<T: TdClientTrait> {
+    /// Start message selection mode (triggered by Up arrow in empty input)
+    fn start_message_selection(&mut self);
+
+    /// Select previous message (up in history = older)
+    fn select_previous_message(&mut self);
+
+    /// Select next message (down in history = newer)
+    fn select_next_message(&mut self);
+
+    /// Get currently selected message
+    fn get_selected_message(&self) -> Option<MessageInfo>;
+
+    /// Start editing the selected message
+    /// Returns true if editing started, false if message cannot be edited
+    fn start_editing_selected(&mut self) -> bool;
+
+    /// Cancel message editing and clear input
+    fn cancel_editing(&mut self);
+
+    /// Check if currently in editing mode
+    fn is_editing(&self) -> bool;
+
+    /// Check if currently in message selection mode
+    fn is_selecting_message(&self) -> bool;
+}
+
+impl<T: TdClientTrait> MessageMethods<T> for App<T> {
+    fn start_message_selection(&mut self) {
+        let total = self.td_client.current_chat_messages().len();
+        if total == 0 {
+            return;
+        }
+        // Начинаем с последнего сообщения (индекс len-1 = самое новое внизу)
+        self.chat_state = ChatState::MessageSelection { selected_index: total - 1 };
+    }
+
+    fn select_previous_message(&mut self) {
+        if let ChatState::MessageSelection { selected_index } = &mut self.chat_state {
+            if *selected_index > 0 {
+                *selected_index -= 1;
+            }
+        }
+    }
+
+    fn select_next_message(&mut self) {
+        let total = self.td_client.current_chat_messages().len();
+        if total == 0 {
+            return;
+        }
+        if let ChatState::MessageSelection { selected_index } = &mut self.chat_state {
+            if *selected_index < total - 1 {
+                *selected_index += 1;
+            } else {
+                // Дошли до самого нового сообщения - выходим из режима выбора
+                self.chat_state = ChatState::Normal;
+            }
+        }
+    }
+
+    fn get_selected_message(&self) -> Option<MessageInfo> {
+        self.chat_state.selected_message_index().and_then(|idx| {
+            self.td_client.current_chat_messages().get(idx).cloned()
+        })
+    }
+
+    fn start_editing_selected(&mut self) -> bool {
+        // Получаем selected_index из текущего состояния
+        let selected_idx = match &self.chat_state {
+            ChatState::MessageSelection { selected_index } => Some(*selected_index),
+            _ => None,
+        };
+
+        if selected_idx.is_none() {
+            return false;
+        }
+
+        // Сначала извлекаем данные из сообщения
+        let msg_data = self.get_selected_message().and_then(|msg| {
+            // Проверяем:
+            // 1. Можно редактировать
+            // 2. Это исходящее сообщение
+            // 3. ID не временный (временные ID в TDLib отрицательные)
+            if msg.can_be_edited() && msg.is_outgoing() && msg.id().as_i64() > 0 {
+                Some((msg.id(), msg.text().to_string(), selected_idx.unwrap()))
+            } else {
+                None
+            }
+        });
+
+        // Затем присваиваем
+        if let Some((id, content, idx)) = msg_data {
+            self.cursor_position = content.chars().count();
+            self.message_input = content;
+            self.chat_state = ChatState::Editing {
+                message_id: id,
+                selected_index: idx,
+            };
+            return true;
+        }
+        false
+    }
+
+    fn cancel_editing(&mut self) {
+        self.chat_state = ChatState::Normal;
+        self.message_input.clear();
+        self.cursor_position = 0;
+    }
+
+    fn is_editing(&self) -> bool {
+        self.chat_state.is_editing()
+    }
+
+    fn is_selecting_message(&self) -> bool {
+        self.chat_state.is_message_selection()
+    }
+}