feat: implement DTW comparison, add data segmentation and persistence, and update QML UI for file imports and graphing.

src/pygui/backend/data/csv_recorder.py

@@ -45,3 +45,23 @@ class CsvRecorder:
         self._file_handle.close()
         path, self._file_handle, self._path = self._path, None, None
         return path
+
+    @staticmethod
+    def write_segment(file_path: str, source_path: str, start_frame: int, end_frame: int) ->bool:
+        """Copy a range of frames from source CSV into a new file.
+
+        Args:
+            file_path: Output CSV path.
+            source_path: Source CSV path with full wafer data
+            start_frame: First frame index (inclusive).
+            end_frame: Last frame index (inclusive)
+
+        Returns:
+            True on success.
+        """
+        import pandas as pd
+        df = pd.read_csv(source_path)
+        segment = df.iloc[start_frame:end_frame + 1]
+        segment.to_csv(file_path, index=False)
+        return True
+