Remove unused code and eliminate build warnings

Removed unused widget subscription system, cache utilities, error variants,
theme functions, and struct fields. Replaced subscription-based widgets
with direct metric filtering. Build now completes with zero warnings.

dashboard/src/ui/widgets/backup.rs

@@ -107,19 +107,6 @@ impl BackupWidget {
         }
     }
     
-    /// Format service status counts
-    fn format_service_counts(&self) -> String {
-        let completed = self.services_completed_count.unwrap_or(0);
-        let failed = self.services_failed_count.unwrap_or(0);
-        let disabled = self.services_disabled_count.unwrap_or(0);
-        let total = self.total_services.unwrap_or(0);
-        
-        if failed > 0 {
-            format!("{}✓ {}✗ {}◯ ({})", completed, failed, disabled, total)
-        } else {
-            format!("{}✓ {}◯ ({})", completed, disabled, total)
-        }
-    }
     
     /// Format disk usage in format "usedGB/totalGB"
     fn format_repo_size(&self) -> String {
@@ -160,30 +147,7 @@ impl BackupWidget {
         }
     }
     
-    /// Get status indicator symbol
-    fn get_status_symbol(&self) -> &str {
-        match self.overall_status {
-            Status::Ok => "●",
-            Status::Warning => "◐",
-            Status::Critical => "◯",
-            Status::Unknown => "?",
-        }
-    }
     
-    /// Format size in GB to appropriate unit (kB/MB/GB)
-    fn format_size_gb(size_gb: f32) -> String {
-        if size_gb >= 1.0 {
-            format!("{:.1}GB", size_gb)
-        } else if size_gb >= 0.001 {
-            let size_mb = size_gb * 1024.0;
-            format!("{:.1}MB", size_mb)
-        } else if size_gb >= 0.000001 {
-            let size_kb = size_gb * 1024.0 * 1024.0;
-            format!("{:.0}kB", size_kb)
-        } else {
-            format!("{:.0}B", size_gb * 1024.0 * 1024.0 * 1024.0)
-        }
-    }
     
     /// Format product name display
     fn format_product_name(&self) -> String {

dashboard/src/ui/widgets/services.rs

@@ -118,36 +118,6 @@ impl ServicesWidget {
                 disk_str)
     }
     
-    /// Format sub-service line (indented, no memory/disk columns) - returns text without icon for span formatting
-    fn format_sub_service_line(&self, name: &str, info: &ServiceInfo) -> String {
-        // Truncate long sub-service names to fit layout (accounting for indentation)
-        let short_name = if name.len() > 18 {
-            format!("{}...", &name[..15])
-        } else {
-            name.to_string()
-        };
-        
-        // Sub-services show latency if available, otherwise status
-        let status_str = if let Some(latency) = info.latency_ms {
-            if latency < 0.0 {
-                "timeout".to_string()
-            } else {
-                format!("{:.0}ms", latency)
-            }
-        } else {
-            match info.widget_status {
-                Status::Ok => "active".to_string(),
-                Status::Warning => "inactive".to_string(), 
-                Status::Critical => "failed".to_string(),
-                Status::Unknown => "unknown".to_string(),
-            }
-        };
-        
-        // Indent sub-services with "  ├─ " prefix (no memory/disk columns)
-        format!("  ├─ {:<20} {:<10}", 
-                short_name,
-                status_str)
-    }
     
     /// Create spans for sub-service with icon next to name
     fn create_sub_service_spans(&self, name: &str, info: &ServiceInfo) -> Vec<ratatui::text::Span<'static>> {