fix: add GetEpochHistory to api_gateway proxy + clippy fixes

- Implement GetEpochHistory forwarding in MonitoringServiceProxy
- Fix clippy integer suffix style (0usize → 0_usize)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

crates/ml/src/trainers/dqn/financials.rs

@@ -103,9 +103,9 @@ pub(crate) fn compute_epoch_financials(
     // Exposure 0,1 = reduce/close (SELL-like), 2 = hold, 3,4 = add/aggressive (BUY-like)
     let total_actions: usize = action_counts.iter().sum();
     let (buy_pct, sell_pct, hold_pct) = if total_actions > 0 {
-        let mut buy = 0usize;
-        let mut sell = 0usize;
-        let mut hold = 0usize;
+        let mut buy = 0_usize;
+        let mut sell = 0_usize;
+        let mut hold = 0_usize;
         for (i, &count) in action_counts.iter().enumerate() {
             let exposure = i / 9; // 0-4
             match exposure {

services/api_gateway/src/grpc/monitoring_proxy.rs

@@ -11,7 +11,8 @@ use tracing::{error, info, instrument};
 use crate::monitoring::monitoring_service_client::MonitoringServiceClient;
 use crate::monitoring::monitoring_service_server::{MonitoringService, MonitoringServiceServer};
 use crate::monitoring::{
-    GetLiveTrainingMetricsRequest, GetLiveTrainingMetricsResponse, StreamTrainingMetricsRequest,
+    GetEpochHistoryRequest, GetEpochHistoryResponse, GetLiveTrainingMetricsRequest,
+    GetLiveTrainingMetricsResponse, StreamTrainingMetricsRequest,
 };
 
 /// Monitoring Service Proxy
@@ -79,6 +80,23 @@ impl MonitoringService for MonitoringServiceProxy {
         info!("StreamTrainingMetrics forwarded successfully");
         Ok(Response::new(boxed_stream))
     }
+
+    #[instrument(skip(self, request), fields(request_id = %uuid::Uuid::new_v4()), err)]
+    async fn get_epoch_history(
+        &self,
+        request: Request<GetEpochHistoryRequest>,
+    ) -> Result<Response<GetEpochHistoryResponse>, Status> {
+        info!("Proxying GetEpochHistory request");
+
+        let mut client = self.client.clone();
+        let response = client.get_epoch_history(request).await.map_err(|e| {
+            error!("Backend GetEpochHistory failed: {}", e);
+            e
+        })?;
+
+        info!("GetEpochHistory forwarded successfully");
+        Ok(response)
+    }
 }
 
 #[cfg(test)]