Replay Tabs:

- Add stability detection and threshold classification features with corresponding tests

src/pygui/backend/frame.py

@@ -6,6 +6,6 @@ from dataclasses import dataclass
 class Frame:
     """One sample across all sensors ata a point in time"""
 
-    seq: int
-    t: float
-    values: list[float]
+    seq: int            # monotonically increasing
+    t: float             # seconds (relative or epoch)
+    values: list[float]  # one per sensor, in sensor-layout order