Fix notification system with proper rate limiting and aggregation

- Add rate limiting using rate_limit_minutes config (was ignored)
- Add aggregation using aggregation_interval_seconds config (was ignored)
- Use smtp_host and smtp_port from config (was hardcoded localhost:25)
- Add trigger_on_warnings and trigger_on_failures config options
- Add recovery_requires_all_ok and suppress_individual_recoveries
- Use check_interval_seconds from config (was hardcoded 30s)
- Expand status tracking to all components (drives, pools, services, backup)
- Move notification checks from every collection to dedicated interval
- Separate alert and recovery notifications with proper email formatting
- Only notify on failed services (Critical), not inactive

dashboard/src/ui/mod.rs

@@ -514,14 +514,6 @@ impl TuiApp {
             true // No host selected is considered offline
         };
 
-        // If host is offline, render wake-up message instead of panels
-        if current_host_offline {
-            self.render_offline_host_message(frame, main_chunks[1]);
-            self.render_btop_title(frame, main_chunks[0], metric_store);
-            self.render_statusbar(frame, main_chunks[2], metric_store);
-            return (main_chunks[0], Rect::default(), Rect::default()); // Return title area and empty areas when offline
-        }
-
         // Left side: system panel only (full height)
         let left_chunks = ratatui::layout::Layout::default()
             .direction(Direction::Vertical)
@@ -531,9 +523,13 @@ impl TuiApp {
         // Render title bar
         self.render_btop_title(frame, main_chunks[0], metric_store);
 
-        // Render system panel
+        // Render system panel or offline message in system panel area
         let system_area = left_chunks[0];
-        self.render_system_panel(frame, system_area, metric_store);
+        if current_host_offline {
+            self.render_offline_host_message(frame, system_area);
+        } else {
+            self.render_system_panel(frame, system_area, metric_store);
+        }
 
         // Render right panel with tabs (Services | Hosts)
         let services_area = content_chunks[1];
@@ -829,9 +825,8 @@ impl TuiApp {
     }
 
 
-    /// Render offline host message with wake-up option
+    /// Render offline host message in system panel area
     fn render_offline_host_message(&self, frame: &mut Frame, area: Rect) {
-        use ratatui::layout::Alignment;
         use ratatui::style::Modifier;
         use ratatui::text::{Line, Span};
         use ratatui::widgets::{Block, Borders, Paragraph};
@@ -849,8 +844,9 @@ impl TuiApp {
 
         // Create message content
         let mut lines = vec![
+            Line::from(""),
             Line::from(Span::styled(
-                format!("Host '{}' is offline", hostname),
+                format!(" Host '{}' is offline", hostname),
                 Style::default().fg(Theme::muted_text()).add_modifier(Modifier::BOLD),
             )),
             Line::from(""),
@@ -858,46 +854,26 @@ impl TuiApp {
 
         if has_mac {
             lines.push(Line::from(Span::styled(
-                "Press 'w' to wake up host",
-                Style::default().fg(Theme::primary_text()).add_modifier(Modifier::BOLD),
+                " Press 'w' to wake up host",
+                Style::default().fg(Theme::primary_text()),
             )));
         } else {
             lines.push(Line::from(Span::styled(
-                "No MAC address configured - cannot wake up",
+                " No MAC address configured",
                 Style::default().fg(Theme::muted_text()),
             )));
         }
 
-        // Create centered message
+        // Render message in system panel with border
         let message = Paragraph::new(lines)
             .block(Block::default()
                 .borders(Borders::ALL)
                 .border_style(Style::default().fg(Theme::muted_text()))
-                .title(" Offline Host ")
+                .title(" Offline ")
                 .title_style(Style::default().fg(Theme::muted_text()).add_modifier(Modifier::BOLD)))
-            .style(Style::default().bg(Theme::background()).fg(Theme::primary_text()))
-            .alignment(Alignment::Center);
+            .style(Style::default().bg(Theme::background()).fg(Theme::primary_text()));
 
-        // Center the message in the available area
-        let popup_area = ratatui::layout::Layout::default()
-            .direction(Direction::Vertical)
-            .constraints([
-                Constraint::Percentage(40),
-                Constraint::Length(6),
-                Constraint::Percentage(40),
-            ])
-            .split(area)[1];
-
-        let popup_area = ratatui::layout::Layout::default()
-            .direction(Direction::Horizontal)
-            .constraints([
-                Constraint::Percentage(25),
-                Constraint::Percentage(50),
-                Constraint::Percentage(25),
-            ])
-            .split(popup_area)[1];
-
-        frame.render_widget(message, popup_area);
+        frame.render_widget(message, area);
     }
 
     /// Parse MAC address string (e.g., "AA:BB:CC:DD:EE:FF") to [u8; 6]