chore: Finalize cleanup phases (docstrings, utility consolidation, dev app isolation)

backend/src/ea_chatbot/utils/plots.py

@@ -3,15 +3,25 @@ import matplotlib.pyplot as plt
 
 def fig_to_bytes(fig: plt.Figure, format: str = "png") -> bytes:
     """
-    Convert a Matplotlib figure to bytes.
+    Convert a Matplotlib figure to a bytes object in the specified format.
     
+    This utility encapsulates the boilerplate logic for saving a figure to an 
+    in-memory buffer and retrieving its binary content.
+
     Args:
-        fig: The Matplotlib figure to convert.
-        format: The image format to use (default: "png").
+        fig: The Matplotlib Figure object to be converted.
+        format: The image format string (e.g., "png", "jpg", "svg"). 
+            Defaults to "png".
         
     Returns:
-        bytes: The image data.
+        The binary image data as a bytes object.
+
+    Raises:
+        ValueError: If an unsupported image format is provided.
     """
     buf = io.BytesIO()
-    fig.savefig(buf, format=format)
+    try:
+        fig.savefig(buf, format=format)
+    except Exception as e:
+        raise ValueError(f"Failed to convert figure to {format}: {str(e)}") from e
     return buf.getvalue()