Clean up unused imports and fix build warnings

- Remove unused imports (Duration, HashMap, SharedError, DateTime, etc.)
- Fix unused variables by prefixing with underscore
- Remove redundant dashboard.toml config file
- Update theme imports to use only needed components
- Maintain all functionality while reducing warnings
- Add srv02 to predefined hosts configuration
- Remove unused broadcast_command methods

agent/src/metrics/mod.rs

@@ -5,7 +5,7 @@ use std::time::Instant;
 use tracing::{info, error, debug};
 
 use crate::config::{CollectorConfig, AgentConfig};
-use crate::collectors::{Collector, cpu::CpuCollector, memory::MemoryCollector, disk::DiskCollector, systemd::SystemdCollector, backup::BackupCollector, cached_collector::CachedCollector};
+use crate::collectors::{Collector, cpu::CpuCollector, memory::MemoryCollector, disk::DiskCollector, systemd::SystemdCollector, backup::BackupCollector};
 use crate::cache::MetricCacheManager;
 
 /// Manages all metric collectors with intelligent caching
@@ -195,7 +195,7 @@ impl MetricCollectionManager {
                     }
                 }
             } else {
-                let elapsed = self.last_collection_times.get(collector_name)
+                let _elapsed = self.last_collection_times.get(collector_name)
                     .map(|t| now.duration_since(*t).as_secs())
                     .unwrap_or(0);
                 // Collector skipped (debug logging disabled for performance)