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/components/message_list.rs

@@ -0,0 +1,116 @@
+//! Shared message list rendering for search and pinned modals
+
+use crate::tdlib::MessageInfo;
+use ratatui::{
+    layout::Alignment,
+    style::{Color, Modifier, Style},
+    text::{Line, Span},
+    widgets::{Block, Borders, Paragraph},
+};
+
+/// Renders a single message item with marker, sender, date, and wrapped text
+pub fn render_message_item(
+    msg: &MessageInfo,
+    is_selected: bool,
+    content_width: usize,
+    max_preview_lines: usize,
+) -> Vec<Line<'static>> {
+    let mut lines = Vec::new();
+
+    // Marker, sender name, and date
+    let marker = if is_selected { "▶ " } else { "  " };
+    let sender_color = if msg.is_outgoing() {
+        Color::Green
+    } else {
+        Color::Cyan
+    };
+    let sender_name = if msg.is_outgoing() {
+        "Вы".to_string()
+    } else {
+        msg.sender_name().to_string()
+    };
+
+    lines.push(Line::from(vec![
+        Span::styled(
+            marker.to_string(),
+            Style::default()
+                .fg(Color::Yellow)
+                .add_modifier(Modifier::BOLD),
+        ),
+        Span::styled(
+            format!("{} ", sender_name),
+            Style::default()
+                .fg(sender_color)
+                .add_modifier(Modifier::BOLD),
+        ),
+        Span::styled(
+            format!("({})", crate::utils::format_datetime(msg.date())),
+            Style::default().fg(Color::Gray),
+        ),
+    ]));
+
+    // Wrapped message text
+    let msg_color = if is_selected {
+        Color::Yellow
+    } else {
+        Color::White
+    };
+    let max_width = content_width.saturating_sub(4);
+    let wrapped = crate::ui::messages::wrap_text_with_offsets(msg.text(), max_width);
+    let wrapped_count = wrapped.len();
+
+    for wrapped_line in wrapped.into_iter().take(max_preview_lines) {
+        lines.push(Line::from(vec![
+            Span::raw("    ".to_string()),
+            Span::styled(wrapped_line.text, Style::default().fg(msg_color)),
+        ]));
+    }
+    if wrapped_count > max_preview_lines {
+        lines.push(Line::from(vec![
+            Span::raw("    ".to_string()),
+            Span::styled("...".to_string(), Style::default().fg(Color::Gray)),
+        ]));
+    }
+
+    lines
+}
+
+/// Calculates scroll offset to keep selected item visible
+pub fn calculate_scroll_offset(
+    selected_index: usize,
+    lines_per_item: usize,
+    visible_height: u16,
+) -> u16 {
+    let visible = visible_height.saturating_sub(2) as usize;
+    let selected_line = selected_index * lines_per_item;
+    if selected_line > visible / 2 {
+        (selected_line - visible / 2) as u16
+    } else {
+        0
+    }
+}
+
+/// Renders a help bar with keyboard shortcuts
+pub fn render_help_bar(shortcuts: &[(&str, &str, Color)], border_color: Color) -> Paragraph<'static> {
+    let mut spans: Vec<Span<'static>> = Vec::new();
+    for (i, (key, label, color)) in shortcuts.iter().enumerate() {
+        if i > 0 {
+            spans.push(Span::raw("  ".to_string()));
+        }
+        spans.push(Span::styled(
+            format!(" {} ", key),
+            Style::default()
+                .fg(*color)
+                .add_modifier(Modifier::BOLD),
+        ));
+        spans.push(Span::raw(label.to_string()));
+    }
+
+    Paragraph::new(Line::from(spans))
+        .block(
+            Block::default()
+                .borders(Borders::ALL)
+                .border_style(Style::default().fg(border_color)),
+        )
+        .alignment(Alignment::Center)
+}