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

studies/202512_GenesysCX/config.py

@@ -0,0 +1,38 @@
+"""
+Study configuration for the Genesys CX Cloud TEI (Forrester, December 2025).
+
+Env keys are *study-scoped* (PALLADIUM_GENESYSCX_*) so this study can coexist
+with the Amazon Connect tool IDs in the same .env. 00_provision.ipynb writes
+them for you.
+"""
+
+from __future__ import annotations
+
+import os
+
+#: Human-friendly study identifier — used in export metadata + filenames.
+STUDY_SLUG = "202512_GenesysCX"
+
+
+def _int_env(name: str) -> int | None:
+    raw = os.getenv(name, "").strip()
+    return int(raw) if raw else None
+
+
+#: TEI Report template public_id (12-char short UUID).
+REPORT_PUBLIC_ID: str = os.getenv("PALLADIUM_GENESYSCX_REPORT_PUBLIC_ID", "")
+
+#: TEI Tool instance public_id.
+TOOL_PUBLIC_ID: str = os.getenv("PALLADIUM_GENESYSCX_TOOL_PUBLIC_ID", "")
+
+#: Default discount rate used for local validation of the study numbers.
+DISCOUNT_RATE = 0.10
+
+#: Analysis horizon (years).
+ANALYSIS_YEARS = 3
+
+#: Athena Proposal PK (a TEI tool attaches to a Proposal OR an Engagement).
+PROPOSAL_ID: int | None = _int_env("PALLADIUM_GENESYSCX_PROPOSAL_ID")
+
+#: Athena Engagement PK (alternative attachment point).
+ENGAGEMENT_ID: int | None = _int_env("PALLADIUM_GENESYSCX_ENGAGEMENT_ID")