fix(bench): resolve borrow-after-move error in bench_throughput

- Changed iteration over operation_counts to use a reference (&operation_counts)
- This prevents moving the HashMap while still needing to access its length
- Fixes compilation error E0382

Author: claude

src/bin/bench_throughput.rs

@@ -395,7 +395,7 @@ fn gather_operation_metrics(
 
     // Create metrics based on detected operations
     // Note: This is a simplified approach. Full instrumentation would require library changes.
-    for (op_name, count) in operation_counts {
+    for (op_name, count) in &operation_counts {
         metrics.push(OperationMetric {
             operation_name: op_name.clone(),
             total_time: total_time / operation_counts.len() as u32, // Simplified distribution