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.

agent/src/collectors/cached_collector.rs

@@ -1,74 +0,0 @@
-use super::{Collector, CollectorError};
-use crate::cache::MetricCacheManager;
-use cm_dashboard_shared::Metric;
-use async_trait::async_trait;
-use std::sync::Arc;
-use tracing::{debug, instrument};
-
-/// Wrapper that adds caching to any collector
-pub struct CachedCollector {
-    name: String,
-    inner: Box<dyn Collector>,
-    cache_manager: Arc<MetricCacheManager>,
-}
-
-impl CachedCollector {
-    pub fn new(
-        name: String,
-        inner: Box<dyn Collector>, 
-        cache_manager: Arc<MetricCacheManager>
-    ) -> Self {
-        Self {
-            name,
-            inner,
-            cache_manager,
-        }
-    }
-}
-
-#[async_trait]
-impl Collector for CachedCollector {
-    fn name(&self) -> &str {
-        &self.name
-    }
-
-    #[instrument(skip(self), fields(collector = %self.name))]
-    async fn collect(&self) -> Result<Vec<Metric>, CollectorError> {
-        // First, get all metrics this collector would normally produce
-        let all_metrics = self.inner.collect().await?;
-        
-        let mut result_metrics = Vec::new();
-        let mut metrics_to_collect = Vec::new();
-        
-        // Check cache for each metric
-        for metric in all_metrics {
-            if let Some(cached_metric) = self.cache_manager.get_cached_metric(&metric.name).await {
-                // Use cached version
-                result_metrics.push(cached_metric);
-                debug!("Using cached metric: {}", metric.name);
-            } else {
-                // Need to collect this metric
-                metrics_to_collect.push(metric.name.clone());
-                result_metrics.push(metric);
-            }
-        }
-
-        // Cache the newly collected metrics
-        for metric in &result_metrics {
-            if metrics_to_collect.contains(&metric.name) {
-                self.cache_manager.cache_metric(metric.clone()).await;
-                debug!("Cached new metric: {} (tier: {}s)", 
-                       metric.name,
-                       self.cache_manager.get_cache_interval(&metric.name));
-            }
-        }
-
-        if !metrics_to_collect.is_empty() {
-            debug!("Collected {} new metrics, used {} cached metrics", 
-                   metrics_to_collect.len(),
-                   result_metrics.len() - metrics_to_collect.len());
-        }
-
-        Ok(result_metrics)
-    }
-}

agent/src/collectors/error.rs

@@ -7,16 +7,4 @@ pub enum CollectorError {
     
     #[error("Failed to parse value '{value}': {error}")]
     Parse { value: String, error: String },
-    
-    #[error("System command failed: {command}: {error}")]
-    CommandFailed { command: String, error: String },
-    
-    #[error("Configuration error: {message}")]
-    Configuration { message: String },
-    
-    #[error("Metric calculation error: {message}")]
-    Calculation { message: String },
-    
-    #[error("Timeout error: operation took longer than {timeout_ms}ms")]
-    Timeout { timeout_ms: u64 },
 }

agent/src/collectors/mod.rs

@@ -2,7 +2,6 @@ use async_trait::async_trait;
 use cm_dashboard_shared::Metric;
 use std::time::Duration;
 
-pub mod cached_collector;
 pub mod cpu;
 pub mod memory;
 pub mod disk;