feat: Enhance inference management with device tracking and telemetry updates

tests/test_telemetry_collector.py

@@ -33,6 +33,9 @@ class TestTelemetryCollector:
         mem_info.rss = 70 * 1024 * 1024    # RSS (larger, includes shared)
         col._process.memory_info.return_value = mem_info
         col._process.cpu_percent.return_value = 0.0
+        # Inference stats — None by default (inference disabled)
+        col._inference_device = None
+        col._inference_time_ms = None
         return col
 
     def test_initial_snapshot_has_zero_fps(self):