chore(tests): clean stale FIXME in test_runner, document lock contention tracking

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

services/trading_service/tests/performance_benchmarks.rs

@@ -261,7 +261,10 @@ impl PerformanceBenchmark {
 
             peak_memory_mb: Self::get_peak_memory_mb(),
             avg_cpu_percent: Self::get_avg_cpu_percent(),
-            lock_contention_count: 0, // TODO: Add lock contention tracking
+            // Contention tracking deferred -- requires instrumenting all RwLock/Mutex
+            // acquisitions with try_lock() fallback counting. For production, use
+            // tokio-metrics or prometheus histograms.
+            lock_contention_count: 0,
         };
 
         Ok(results)

tests/test_runner.rs

@@ -12,13 +12,8 @@ use std::collections::HashMap;
 use std::sync::atomic::{AtomicU64, Ordering};
 use std::time::{Duration, Instant};
 
-// Import from the tests library crate (lib.rs)
-// Note: test_runner is a binary, so it imports from the tests library
-// FIXME: critical_tests crate doesn't exist - these modules are not available
-// use critical_tests::safety::{SafeTestError, SafeTestResult};
-// use critical_tests::helpers::mock_implementations::{MockPerformanceMonitor, PerformanceStats};
-
-// Define types locally since critical_tests doesn't exist
+// SafeTestError, SafeTestResult, PerformanceStats, and MockPerformanceMonitor are
+// defined locally below rather than imported from an external crate.
 /// Result type for safe test execution with custom error handling
 pub type SafeTestResult<T> = Result<T, SafeTestError>;