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

shared/src/metrics.rs

@@ -1,5 +1,5 @@
 use serde::{Deserialize, Serialize};
-use chrono::{DateTime, Utc};
+use chrono::Utc;
 
 /// Individual metric with value, status, and metadata
 #[derive(Debug, Clone, Serialize, Deserialize)]