refactor(types): Phase 4 type hint sweep — core modules

performance_monitor.py

@@ -1,6 +1,8 @@
+from __future__ import annotations
 import time
 import psutil
 import threading
+from typing import Any
 
 class PerformanceMonitor:
  def __init__(self) -> None:
@@ -98,7 +100,7 @@ class PerformanceMonitor:
    self._last_alert_time = now
    self.alert_callback("; ".join(alerts))
 
- def get_metrics(self):
+ def get_metrics(self) -> dict[str, Any]:
   with self._cpu_lock:
    cpu_usage = self._cpu_usage
   metrics = {