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/config/keybindings.rs

@@ -230,8 +230,8 @@ impl Keybindings {
 
         // Profile
         bindings.insert(Command::OpenProfile, vec![
-            KeyBinding::new(KeyCode::Char('i')),
-            KeyBinding::new(KeyCode::Char('ш')), // RU
+            KeyBinding::with_ctrl(KeyCode::Char('i')),
+            KeyBinding::with_ctrl(KeyCode::Char('ш')), // RU
         ]);
 
         Self { bindings }

src/config/mod.rs

@@ -34,6 +34,10 @@ pub struct Config {
     /// Горячие клавиши.
     #[serde(default)]
     pub keybindings: Keybindings,
+
+    /// Настройки desktop notifications.
+    #[serde(default)]
+    pub notifications: NotificationsConfig,
 }
 
 /// Общие настройки приложения.
@@ -71,6 +75,31 @@ pub struct ColorsConfig {
     pub reaction_other: String,
 }
 
+/// Настройки desktop notifications.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct NotificationsConfig {
+    /// Включить/выключить уведомления
+    #[serde(default = "default_notifications_enabled")]
+    pub enabled: bool,
+
+    /// Уведомлять только при @упоминаниях
+    #[serde(default)]
+    pub only_mentions: bool,
+
+    /// Показывать превью текста сообщения
+    #[serde(default = "default_show_preview")]
+    pub show_preview: bool,
+
+    /// Продолжительность показа уведомления (миллисекунды)
+    /// 0 = системное значение по умолчанию
+    #[serde(default = "default_notification_timeout")]
+    pub timeout_ms: i32,
+
+    /// Уровень важности: "low", "normal", "critical"
+    #[serde(default = "default_notification_urgency")]
+    pub urgency: String,
+}
+
 // Дефолтные значения
 fn default_timezone() -> String {
     "+03:00".to_string()
@@ -96,6 +125,22 @@ fn default_reaction_other_color() -> String {
     "gray".to_string()
 }
 
+fn default_notifications_enabled() -> bool {
+    true
+}
+
+fn default_show_preview() -> bool {
+    true
+}
+
+fn default_notification_timeout() -> i32 {
+    5000 // 5 seconds
+}
+
+fn default_notification_urgency() -> String {
+    "normal".to_string()
+}
+
 impl Default for GeneralConfig {
     fn default() -> Self {
         Self { timezone: default_timezone() }
@@ -114,6 +159,17 @@ impl Default for ColorsConfig {
     }
 }
 
+impl Default for NotificationsConfig {
+    fn default() -> Self {
+        Self {
+            enabled: default_notifications_enabled(),
+            only_mentions: false,
+            show_preview: default_show_preview(),
+            timeout_ms: default_notification_timeout(),
+            urgency: default_notification_urgency(),
+        }
+    }
+}
 
 impl Default for Config {
     fn default() -> Self {
@@ -121,6 +177,7 @@ impl Default for Config {
             general: GeneralConfig::default(),
             colors: ColorsConfig::default(),
             keybindings: Keybindings::default(),
+            notifications: NotificationsConfig::default(),
         }
     }
 }