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/client.rs

@@ -15,6 +15,7 @@ use super::messages::MessageManager;
 use super::reactions::ReactionManager;
 use super::types::{ChatInfo, FolderInfo, MessageInfo, NetworkState, ProfileInfo, UserOnlineStatus};
 use super::users::UserCache;
+use crate::notifications::NotificationManager;
 
 /// TDLib client wrapper for Telegram integration.
 ///
@@ -52,6 +53,7 @@ pub struct TdClient {
     pub message_manager: MessageManager,
     pub user_cache: UserCache,
     pub reaction_manager: ReactionManager,
+    pub notification_manager: NotificationManager,
 
     // Состояние сети
     pub network_state: NetworkState,
@@ -93,10 +95,27 @@ impl TdClient {
             message_manager: MessageManager::new(client_id),
             user_cache: UserCache::new(client_id),
             reaction_manager: ReactionManager::new(client_id),
+            notification_manager: NotificationManager::new(),
             network_state: NetworkState::Connecting,
         }
     }
 
+    /// Configures notification manager from app config
+    pub fn configure_notifications(&mut self, config: &crate::config::NotificationsConfig) {
+        self.notification_manager.set_enabled(config.enabled);
+        self.notification_manager.set_only_mentions(config.only_mentions);
+        self.notification_manager.set_timeout(config.timeout_ms);
+        self.notification_manager.set_urgency(config.urgency.clone());
+        // Note: show_preview is used when formatting notification body
+    }
+
+    /// Synchronizes muted chats from Telegram to notification manager.
+    ///
+    /// Should be called after chats are loaded to ensure muted chats don't trigger notifications.
+    pub fn sync_notification_muted_chats(&mut self) {
+        self.notification_manager.sync_muted_chats(&self.chat_manager.chats);
+    }
+
     // Делегирование к auth
 
     /// Sends phone number for authentication.