refactor: complete Phase 13 deep architecture refactoring (etaps 3-7)

Split monolithic files into modular architecture:
- ui/messages.rs (893→365 lines): extract modals/, compose_bar.rs
- tdlib/messages.rs (836→3 files): split into messages/mod, convert, operations
- config/mod.rs (642→3 files): extract validation.rs, loader.rs
- Code duplication cleanup: shared components, ~220 lines removed
- Documentation: PROJECT_STRUCTURE.md rewrite, 16 files got //! docs

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

src/ui/modals/search.rs

@@ -0,0 +1,117 @@
+//! Message search modal
+
+use crate::app::App;
+use crate::tdlib::TdClientTrait;
+use crate::ui::components::{render_message_item, calculate_scroll_offset, render_help_bar};
+use ratatui::{
+    layout::{Constraint, Direction, Layout, Rect},
+    style::{Color, Modifier, Style},
+    text::{Line, Span},
+    widgets::{Block, Borders, Paragraph},
+    Frame,
+};
+
+/// Renders message search mode
+pub fn render<T: TdClientTrait>(f: &mut Frame, area: Rect, app: &App<T>) {
+    // Извлекаем данные из ChatState
+    let (query, results, selected_index) =
+        if let crate::app::ChatState::SearchInChat {
+            query,
+            results,
+            selected_index,
+        } = &app.chat_state
+        {
+            (query.as_str(), results.as_slice(), *selected_index)
+        } else {
+            return; // Некорректное состояние, не рендерим
+        };
+
+    let chunks = Layout::default()
+        .direction(Direction::Vertical)
+        .constraints([
+            Constraint::Length(3), // Search input
+            Constraint::Min(0),    // Search results
+            Constraint::Length(3), // Help bar
+        ])
+        .split(area);
+
+    // Search input
+    let total = results.len();
+    let current = if total > 0 {
+        selected_index + 1
+    } else {
+        0
+    };
+
+    let input_line = if query.is_empty() {
+        Line::from(vec![
+            Span::styled("🔍 ", Style::default().fg(Color::Yellow)),
+            Span::styled("█", Style::default().fg(Color::Yellow)),
+            Span::styled(" Введите текст для поиска...", Style::default().fg(Color::Gray)),
+        ])
+    } else {
+        Line::from(vec![
+            Span::styled("🔍 ", Style::default().fg(Color::Yellow)),
+            Span::styled(query, Style::default().fg(Color::White)),
+            Span::styled("█", Style::default().fg(Color::Yellow)),
+            Span::styled(format!("  ({}/{})", current, total), Style::default().fg(Color::Gray)),
+        ])
+    };
+
+    let search_input = Paragraph::new(input_line).block(
+        Block::default()
+            .borders(Borders::ALL)
+            .border_style(Style::default().fg(Color::Yellow))
+            .title(" Поиск по сообщениям ")
+            .title_style(
+                Style::default()
+                    .fg(Color::Yellow)
+                    .add_modifier(Modifier::BOLD),
+            ),
+    );
+    f.render_widget(search_input, chunks[0]);
+
+    // Search results
+    let content_width = chunks[1].width.saturating_sub(2) as usize;
+    let mut lines: Vec<Line> = Vec::new();
+
+    if results.is_empty() {
+        if !query.is_empty() {
+            lines.push(Line::from(Span::styled(
+                "Ничего не найдено",
+                Style::default().fg(Color::Gray),
+            )));
+        }
+    } else {
+        for (idx, msg) in results.iter().enumerate() {
+            if idx > 0 {
+                lines.push(Line::from(""));
+            }
+            lines.extend(render_message_item(msg, idx == selected_index, content_width, 2));
+        }
+    }
+
+    // Скролл к выбранному результату
+    let scroll_offset = calculate_scroll_offset(selected_index, 4, chunks[1].height);
+
+    let results_widget = Paragraph::new(lines)
+        .block(
+            Block::default()
+                .borders(Borders::ALL)
+                .border_style(Style::default().fg(Color::Yellow)),
+        )
+        .scroll((scroll_offset, 0));
+    f.render_widget(results_widget, chunks[1]);
+
+    // Help bar
+    let help = render_help_bar(
+        &[
+            ("↑↓", "навигация", Color::Yellow),
+            ("n/N", "след./пред.", Color::Yellow),
+            ("Enter", "перейти", Color::Green),
+            ("Esc", "выход", Color::Red),
+        ],
+        Color::Yellow,
+    );
+    f.render_widget(help, chunks[2]);
+}