feat(debug): add debug read with CSV export

- Parse F1 debug data via family-independent temp formula
  (bits 4-14 scaled by 2**(i-8), sign at bit 0)
- Save sensor+debug temps side-by-side to debug_info.csv
- Wire READ DEBUG button in StatusActionsPanel
- Rename ReplayChart → RunChart; move into GraphTab
- Extract PanelBox/SectionTitle/PanelSlider in ReadoutPanel
  to cut ~300 lines of duplicated styling
- Add rightRailWidth token to Theme for consistent rail sizing
- Wrap ReadoutPanel in ScrollView so Thresholds card stays
  reachable when E-C delta rows appear

tests/test_data_parser.py

@@ -3,11 +3,14 @@
 import pytest
 
 from pygui.serialcomm.data_parser import (
+    _convert_debug_temp,
     _convert_hex_to_temp,
+    convert_to_debug_temperatures,
     convert_to_temperatures,
     csv_column_count,
     parse_binary_data,
     remove_trailing_zeros,
+    save_debug_csv,
     save_to_csv,
 )
 
@@ -321,3 +324,97 @@ class TestSaveToCsv:
         assert len(headers) == 244, f"expected 244 cols, got {len(headers)}"
         assert len(data_row) == 244, f"expected 244 data cols, got {len(data_row)}"
         assert data_row[243] == "243.0", "last column value must be preserved"
+
+
+# ── Debug temperature conversion ───────────────────────────────────────────────
+
+
+class TestConvertDebugTemp:
+    """Spot-check known hex → debug temperature values.
+
+    Reference values derived from C#'s ConvertBinaryArrayToDebugTemp
+    (bits 4-14 scaled by 2**(i-8), sign at bit 0 — no family branching).
+    """
+
+    def test_zero_hex_gives_zero(self):
+        assert _convert_debug_temp("0000") == 0.0
+
+    def test_bit8_gives_one(self):
+        # bit index 8 set (value 0x0080) → contributes 2**(8-8) = 1.0
+        assert _convert_debug_temp("0080") == pytest.approx(1.0, abs=0.01)
+
+    def test_sign_bit_negates(self):
+        # sign bit (bit 0) + bit 8 → -1.0
+        assert _convert_debug_temp("8080") == pytest.approx(-1.0, abs=0.01)
+
+    def test_no_family_branching(self):
+        # Debug conversion takes no family code — same result regardless
+        assert _convert_debug_temp("0080") == _convert_debug_temp("0080")
+
+
+class TestConvertToDebugTemperatures:
+    def test_returns_same_shape(self):
+        hex_data = [["0080", "0000"], ["8080", "0000"]]
+        result = convert_to_debug_temperatures(hex_data)
+        assert len(result) == 2
+        assert len(result[0]) == 2
+
+    def test_values_are_strings(self):
+        result = convert_to_debug_temperatures([["0080"]])
+        assert isinstance(result[0][0], str)
+
+    def test_converts_known_value(self):
+        result = convert_to_debug_temperatures([["0080"]])
+        assert float(result[0][0]) == pytest.approx(1.0, abs=0.01)
+
+
+# ── Debug CSV export ────────────────────────────────────────────────────────────
+
+
+class TestSaveDebugCsv:
+    def test_creates_file_with_fixed_name(self, tmp_path):
+        result = save_debug_csv([["25.0"]], [["1.0"]], str(tmp_path))
+        assert result is not None
+        assert result.endswith("debug_info.csv")
+
+    def test_header_alternates_sensor_and_debug(self, tmp_path):
+        result = save_debug_csv([["25.0", "24.5"]], [["1.0", "2.0"]], str(tmp_path))
+        assert result is not None
+        header = open(result).readline().strip()
+        assert header == "Sensor1,Debug1,Sensor2,Debug2"
+
+    def test_data_row_alternates_values(self, tmp_path):
+        result = save_debug_csv([["25.0", "24.5"]], [["1.0", "2.0"]], str(tmp_path))
+        assert result is not None
+        lines = open(result).readlines()
+        assert lines[1].strip() == "25.0,1.0,24.5,2.0"
+
+    def test_truncates_to_shorter_row_count(self, tmp_path):
+        temp_data = [["25.0"], ["24.0"], ["23.0"]]
+        debug_data = [["1.0"], ["2.0"]]
+        result = save_debug_csv(temp_data, debug_data, str(tmp_path))
+        assert result is not None
+        lines = open(result).readlines()
+        assert len(lines) == 3  # 1 header + 2 data rows (shorter of the two)
+
+    def test_truncates_to_shorter_column_count(self, tmp_path):
+        temp_data = [["25.0", "24.0", "23.0"]]
+        debug_data = [["1.0", "2.0"]]
+        result = save_debug_csv(temp_data, debug_data, str(tmp_path))
+        assert result is not None
+        header = open(result).readline().strip()
+        assert header == "Sensor1,Debug1,Sensor2,Debug2"
+
+    def test_returns_none_on_empty_temp_data(self, tmp_path):
+        assert save_debug_csv([], [["1.0"]], str(tmp_path)) is None
+
+    def test_returns_none_on_empty_debug_data(self, tmp_path):
+        assert save_debug_csv([["25.0"]], [], str(tmp_path)) is None
+
+    def test_creates_output_dir_if_missing(self, tmp_path):
+        nested = str(tmp_path / "a" / "b")
+        result = save_debug_csv([["25.0"]], [["1.0"]], nested)
+        assert result is not None
+        from pathlib import Path
+
+        assert Path(result).exists()