feat(backtesting_service): wire equity curve total_count and add stop_backtest logging

- Replace hardcoded `total_count: 0` with `summaries.len() as u32` in list_backtests
- Add tracing::warn! in get_backtest_results when equity_curve is returned empty
- Add tracing::warn! in stop_backtest noting task cancellation is not yet implemented
- Import `warn` from tracing alongside existing debug/error/info imports

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

services/backtesting_service/src/service.rs

@@ -5,7 +5,7 @@ use std::collections::HashMap;
 use std::sync::Arc;
 use tokio::sync::{broadcast, RwLock};
 use tonic::{Request, Response, Status};
-use tracing::{debug, error, info};
+use tracing::{debug, error, info, warn};
 use uuid::Uuid;
 
 use crate::foxhunt::tli::{backtesting_service_server::BacktestingService, *};
@@ -570,7 +570,10 @@ impl BacktestingService for BacktestingServiceImpl {
             backtest_id: req.backtest_id,
             metrics: proto_metrics,
             trades: proto_trades,
-            equity_curve: Vec::new(),     // TODO: Implement equity curve
+            equity_curve: {
+                warn!("Equity curve not yet populated from backtest results");
+                Vec::new()
+            }, // TODO: Implement equity curve
             drawdown_periods: Vec::new(), // TODO: Implement drawdown periods
         }))
     }
@@ -593,10 +596,11 @@ impl BacktestingService for BacktestingServiceImpl {
             .map_err(|e| Status::internal(format!("Failed to list backtests: {}", e)))?;
 
         let summaries: Vec<BacktestSummary> = backtests.into_iter().map(|bt| bt.into()).collect();
+        let total_count = summaries.len() as u32;
 
         Ok(Response::new(ListBacktestsResponse {
             backtests: summaries,
-            total_count: 0, // TODO: Implement total count
+            total_count,
         }))
     }
 
@@ -655,7 +659,12 @@ impl BacktestingService for BacktestingServiceImpl {
             }
         }
 
-        // TODO: Actually stop the running backtest task
+        // Task cancellation not yet implemented — the spawned tokio task will run to completion.
+        // When a CancellationToken or JoinHandle is stored in BacktestContext this can be wired up.
+        warn!(
+            "stop_backtest: task cancellation not yet implemented for {}",
+            req.backtest_id
+        );
 
         Ok(Response::new(StopBacktestResponse {
             success: true,