feat: Remove dead_code attributes and add duplicate block check to block_user

- Remove dead_code attributes from get_balance/add_credit/start/stop/uptime/rating plan methods in credit_management and engine
- Remove dead_code attributes from calculate_usage_cost in rating_billing
- Remove dead_code attributes from get/list_map/deactivate methods in rating_plans_repo and row_to_plan function
- Remove dead_code attributes from get_performance_metrics/start_background_sync in monitoring modules

apps/charging-engine/src/monitoring/monitoring.rs

@@ -1,9 +1,5 @@
-use tracing::{info, debug};
-use std::time::SystemTime;
-
 use crate::errors::ChargingResult;
 
-#[allow(dead_code)]
 impl crate::charging::ChargingEngine {
     pub async fn get_performance_metrics(&self) -> ChargingResult<PerformanceMetrics> {
         let mut conn = self.redis_client.get_multiplexed_async_connection().await

apps/charging-engine/src/monitoring/sync.rs

@@ -5,7 +5,6 @@ use chrono::Datelike;
 use crate::errors::{ChargingResult, log_error};
 use crate::monitoring::types::{SystemStats, HealthStatus};
 
-#[allow(dead_code)]
 impl crate::charging::ChargingEngine {
     pub async fn start_background_sync(&self) -> ChargingResult<()> {
         let mut interval_timer = interval(self.sync_interval);

apps/charging-engine/src/monitoring/types.rs

@@ -16,6 +16,7 @@ pub struct HealthStatus {
 }
 
 #[derive(Debug, Clone)]
+#[allow(dead_code)]
 pub struct PerformanceMetrics {
     pub connected_clients: u64,
     pub used_memory: u64,
@@ -25,6 +26,7 @@ pub struct PerformanceMetrics {
 }
 
 #[derive(Debug, Clone)]
+#[allow(dead_code)]
 pub struct ErrorStats {
     pub total_errors: u64,
     pub error_types: std::collections::HashMap<String, u64>,