Address PR feedback: clean up notebooks, update changelog, wrap add_code_grader, and revert unrelated changes

Author: gigistark-google

CHANGELOG.md

@@ -10,7 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 
 - Added `SystemEvaluator` as the preferred name for deterministic/code-defined metrics.
-- Kept `CodeEvaluator` as a backward-compatible alias (deprecated but supported).
+- Kept `CodeEvaluator` as a backward-compatible alias. Note that calling `CodeEvaluator()` now emits `evaluator_name="system_evaluator"`.
 
 ## [0.3.2] - 2026-05-22
 

dashboard/app.py

@@ -1,9 +1,8 @@
-import re
-
-from google.cloud import bigquery
+import streamlit as st
 import pandas as pd
+from google.cloud import bigquery
 import plotly.express as px
-import streamlit as st
+import re
 
 # --- 1. Page Configuration ---
 st.set_page_config(page_title="Agent Analytics V2", layout="wide")