feat: implement overlay architecture with IOverlayLayer interface and telemetry overlay

tests/test_telemetry_collector.py

@@ -24,7 +24,12 @@ class TestTelemetryCollector:
         col._fps_window = deque()
         col._fps_window_size_s = 1.0
         col._process = MagicMock()
-        col._process.memory_info.return_value.rss = 50 * 1024 * 1024  # 50 MB
+        # Simulate Windows: wset is present and takes priority over rss
+        mem_info = MagicMock()
+        mem_info.wset = 50 * 1024 * 1024   # 50 MB private working set
+        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
         return col
 
     def test_initial_snapshot_has_zero_fps(self):