Remove unused code and eliminate compiler warnings

- Remove unused fields from CommandStatus variants
- Clean up unused methods and unused collector fields
- Fix lifetime syntax warning in SystemWidget
- Delete unused cache module completely
- Remove redundant render methods from widgets

All agent and dashboard warnings eliminated while preserving
panel switching and scrolling functionality.

agent/src/status/mod.rs

@@ -70,7 +70,7 @@ impl HostStatusManager {
 
     /// Update the status of a specific service and recalculate host status
     /// Updates real-time status and buffers changes for email notifications
-    pub fn update_service_status(&mut self, service: String, status: Status, cache_manager: Option<&crate::cache::MetricCacheManager>) {
+    pub fn update_service_status(&mut self, service: String, status: Status) {
         if !self.config.enabled {
             return;
         }
@@ -82,14 +82,6 @@ impl HostStatusManager {
             return;
         }
 
-        // Save cache when status changes (clone cache manager reference for async)
-        if let Some(cache) = cache_manager {
-            let cache = cache.clone();
-            tokio::spawn(async move {
-                cache.save_to_disk().await;
-            });
-        }
-
         // Initialize batch if this is the first change
         if self.batch_start_time.is_none() {
             self.batch_start_time = Some(Instant::now());
@@ -169,9 +161,9 @@ impl HostStatusManager {
 
 
     /// Process a metric - updates status (notifications handled separately via batching)
-    pub async fn process_metric(&mut self, metric: &Metric, _notification_manager: &mut crate::notifications::NotificationManager, cache_manager: &crate::cache::MetricCacheManager) {
+    pub async fn process_metric(&mut self, metric: &Metric, _notification_manager: &mut crate::notifications::NotificationManager) {
         // Just update status - notifications are handled by process_pending_notifications
-        self.update_service_status(metric.name.clone(), metric.status, Some(cache_manager));
+        self.update_service_status(metric.name.clone(), metric.status);
     }
 
     /// Process pending notifications - call this at notification intervals