feat: implement desktop notifications with comprehensive filtering

Implemented Phase 10 (Desktop Notifications) with three stages:
notify-rust integration, smart filtering, and production polish.

Stage 1 - Base Implementation:
- Add NotificationManager module (src/notifications.rs, 350+ lines)
- Integrate notify-rust 4.11 with feature flag "notifications"
- Implement NotificationsConfig in config.toml (enabled, only_mentions, show_preview)
- Add notification_manager field to TdClient
- Create configure_notifications() method for config integration
- Hook into handle_new_message_update() to send notifications
- Send notifications for messages outside current chat
- Format notification body with sender name and message preview

Stage 2 - Smart Filtering:
- Sync muted chats from Telegram (sync_muted_chats method)
- Filter muted chats from notifications automatically
- Add MessageInfo::has_mention() to detect @username mentions
- Implement only_mentions filter (notify only when mentioned)
- Beautify media labels with emojis (📷 📹 🎤 🎨 📎 etc.)
- Support 10+ media types in notification preview

Stage 3 - Production Polish:
- Add graceful error handling (no panics on notification failure)
- Implement comprehensive logging (tracing::debug!/warn!)
- Add timeout_ms configuration (0 = system default)
- Add urgency configuration (low/normal/critical, Linux only)
- Platform-specific #[cfg] for urgency support
- Log all notification skip reasons at debug level

Hotkey Change:
- Move profile view from 'i' to Ctrl+i to avoid conflicts

Technical Details:
- Cross-platform support (macOS, Linux, Windows)
- Feature flag for optional notifications support
- Graceful fallback when notifications unavailable
- LRU-friendly muted chats sync
- Test coverage for all core notification logic
- All 75 tests passing

Files Changed:
- NEW: src/notifications.rs - Complete NotificationManager
- NEW: config.example.toml - Example configuration with notifications
- Modified: Cargo.toml - Add notify-rust 4.11 dependency
- Modified: src/config/mod.rs - Add NotificationsConfig struct
- Modified: src/tdlib/types.rs - Add has_mention() method
- Modified: src/tdlib/client.rs - Add notification integration
- Modified: src/tdlib/update_handlers.rs - Hook notifications
- Modified: src/config/keybindings.rs - Change profile to Ctrl+i
- Modified: tests/* - Add notification config to tests

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

src/tdlib/update_handlers.rs

@@ -19,12 +19,29 @@ use super::types::ReactionInfo;
 
 /// Обрабатывает Update::NewMessage - добавление нового сообщения
 pub fn handle_new_message_update(client: &mut TdClient, new_msg: UpdateNewMessage) {
-    // Добавляем новое сообщение если это текущий открытый чат
     let chat_id = ChatId::new(new_msg.message.chat_id);
+
+    // Если сообщение НЕ для текущего открытого чата - отправляем уведомление
     if Some(chat_id) != client.current_chat_id() {
+        // Find and clone chat info to avoid borrow checker issues
+        if let Some(chat) = client.chats().iter().find(|c| c.id == chat_id).cloned() {
+            let msg_info = crate::tdlib::message_converter::convert_message(client, &new_msg.message, chat_id);
+
+            // Get sender name (from message or user cache)
+            let sender_name = msg_info.sender_name();
+
+            // Send notification
+            let _ = client.notification_manager.notify_new_message(
+                &chat,
+                &msg_info,
+                sender_name,
+            );
+        }
         return;
     }
 
+    // Добавляем новое сообщение если это текущий открытый чат
+
     let msg_info = crate::tdlib::message_converter::convert_message(client, &new_msg.message, chat_id);
     let msg_id = msg_info.id();
     let is_incoming = !msg_info.is_outgoing();