feat: add GenesysCX study and fix Streamlit chart key collisions

- Add 202512_GenesysCX TEI study (config, seed data, notebooks, README)
  with NPV $10.8M / ROI 266% including AI-token cost line
- Add explicit `key` parameter to all chart wrappers in app/components
  to prevent StreamlitDuplicateElementId errors when the same figure
  type renders across Summary/Benefits/Costs tabs
- Render benefits bar and cost pie charts on their respective tabs
- Add benefits_vs_costs_by_year chart wrapper

app/views/benefits.py

@@ -4,6 +4,7 @@ from __future__ import annotations
 
 import streamlit as st
 
+from app.components import charts
 from app.components.tables import df_to_values, value_editor
 from app.utils import icon
 
@@ -50,3 +51,7 @@ def render(client: TEIClient, tool: dict) -> None:
             "applied at calculate time. Use the Recalculate button in the "
             "sidebar after saving to refresh the summary."
         )
+
+    if values:
+        st.divider()
+        charts.benefits_bar(values, key=f"benefits_tab_bar_{public_id}")