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

src/pygui/serialcomm/data_parser.py

@@ -107,6 +107,23 @@ def _convert_aep(binary_bits: list[int]) -> float:
     return result
 
 
+def _convert_debug_temp(hex_str: str) -> float:
+    """Convert a 4-char hex string to a debug/cold-junction temperature.
+
+    Mirrors C#'s ConvertBinaryArrayToDebugTemp: bits 4-14 scaled by
+    2**(i-8), sign bit at bit 0. No family-code branching — this formula
+    applies regardless of wafer family, unlike _convert_hex_to_temp.
+    """
+    bits = _hex_to_binary(hex_str)
+    value = 0.0
+    for i in range(4, 15):
+        if bits[i]:
+            value += 2.0 ** (i - 8)
+    if bits[0]:
+        value = -value
+    return round(value, 2)
+
+
 def _convert_hex_to_temp(hex_str: str, family_code: str) -> float:
     """Convert a singi hale 4-char hex string to a float temperature."""
     bits = _hex_to_binary(hex_str)
@@ -225,6 +242,15 @@ def convert_to_temperatures(
     return temp_value
 
 
+def convert_to_debug_temperatures(hex_data: list[list[str]]) -> list[list[str]]:
+    """Convert debug/cold-junction hex values to temperature strings.
+
+    Same shape contract as convert_to_temperatures, but uses the
+    family-independent debug formula (_convert_debug_temp).
+    """
+    return [[str(_convert_debug_temp(h)) for h in row] for row in hex_data]
+
+
 def remove_trailing_zeros(data: list[list[str]]) -> None:
     """Remove rows of all-zero values from the end of data (in-place).
 
@@ -294,3 +320,46 @@ def save_to_csv(
     except Exception as exc:
         log.error("CSV save failed: %s", exc)
         return None
+
+
+def save_debug_csv(
+    temp_data: list[list[str]],
+    debug_data: list[list[str]],
+    output_dir: str,
+) -> Optional[str]:
+    """Save sensor + debug temperatures side-by-side to debug_info.csv.
+
+    Mirrors C#'s writeDebugCSV: alternating Sensor{j+1},Debug{j+1} columns,
+    truncated to the shorter of the two row/column counts. Fixed filename
+    (not timestamped), unlike save_to_csv.
+
+    Args:
+        temp_data: 2D array of sensor temperature strings (D1, decoded via
+            convert_to_temperatures).
+        debug_data: 2D array of debug temperature strings (F1, decoded via
+            convert_to_debug_temperatures).
+        output_dir: Directory to save the CSV file.
+
+    Returns:
+        Full file path on success, None on empty input or write failure.
+    """
+    if not temp_data or not debug_data:
+        log.error("Debug CSV save failed: temp or debug data is empty")
+        return None
+    try:
+        os.makedirs(output_dir, exist_ok=True)
+        num_cols = min(len(temp_data[0]), len(debug_data[0]))
+        num_rows = min(len(temp_data), len(debug_data))
+        filepath = os.path.join(output_dir, "debug_info.csv")
+        with open(filepath, "w", encoding="utf-8") as f:
+            headers = [f"Sensor{j + 1},Debug{j + 1}" for j in range(num_cols)]
+            f.write(",".join(headers) + "\n")
+            for i in range(num_rows):
+                row = [f"{temp_data[i][j]},{debug_data[i][j]}" for j in range(num_cols)]
+                f.write(",".join(row) + "\n")
+
+        log.info("Saved debug CSV: %d rows × %d cols to %s", num_rows, num_cols, filepath)
+        return filepath
+    except Exception as exc:
+        log.error("Debug CSV save failed: %s", exc)
+        return None