feat(graph): add graph tab for whole-run data

Provides a static line chart plotting multi-sensor temperature values
over time when a session file is loaded.

tests/test_frame_player.py

@@ -1,5 +1,5 @@
 from pygui.backend.models.frame import Frame
-from pygui.backend.models.frame_player import FramePlayer
+from pygui.backend.models.frame_player import FramePlayer, all_sensor_series
 
 
 def frames(n):
@@ -29,3 +29,24 @@ def test_at_end():
     assert not p.at_end
     p.seek(1)
     assert p.at_end
+
+def test_frames_property_exposes_loaded_frames():
+    p = FramePlayer(); p.load(frames(3))
+    assert p.frames == tuple(frames(3))
+
+
+# ---- all_sensor_series (Graph tab whole-run assembly) ----
+
+def test_all_sensor_series_empty_frames():
+    assert all_sensor_series([]) == ([], [])
+
+
+def test_all_sensor_series_names_and_columns():
+    fs = [
+        Frame(seq=0, time=0.0, values=[150.0, 148.0]),
+        Frame(seq=1, time=1.0, values=[151.0, 147.5]),
+        Frame(seq=2, time=2.0, values=[152.0, 147.0]),
+    ]
+    names, series = all_sensor_series(fs)
+    assert names == ["Sensor 1", "Sensor 2"]
+    assert series == [[150.0, 151.0, 152.0], [148.0, 147.5, 147.0]]