feat: update ctm-token-calculator to use Mercury and notebook deliverables

Replace Streamlit and JupyterLab commands with Mercury for serving interactive
notebooks as web apps. Update README to reflect new architecture where
notebooks are the primary deliverables, utilizing Mercury input widgets for
live client tuning. Add export_report.py script to generate LLM-readable
HTML/Markdown reports from the notebooks. Update corrected business case
notebook to include Mercury dependency and usage instructions.

studies/202512_GenesysCX/ctm-token-calculator/config.toml

@@ -0,0 +1,43 @@
+# Mercury app-shell theme — matched to the notebooks' chart chrome
+# (same warm-neutral surfaces and capability blue as the figures).
+#
+# Loaded from the directory where you launch `mercury` (this project root);
+# restart the server to apply changes. Full key list: mercury/config.py
+# DEFAULT_THEME — anything omitted is derived from the values below.
+
+[main]
+title = "CTM × Genesys — Business Case"
+favicon_emoji = "📊"
+footer = "CTM × Genesys CCaaS study"
+notebooks_button_label = "Analyses"
+
+[welcome]
+header = "CTM × Genesys CCaaS"
+message = """
+Interactive business-case notebooks. **Corrected Business Case** keeps
+Genesys's claimed benefits verbatim and adds the costs the pitch omitted —
+tune the 🟡 inputs live for the client, then export the personalized report
+source with `python scripts/export_report.py`.
+"""
+
+[theme]
+# text — same ink scale as the figures
+font_family = "system-ui, -apple-system, 'Segoe UI', sans-serif"
+heading_font_family = "system-ui, -apple-system, 'Segoe UI', sans-serif"
+text_color = "#0b0b0b"
+muted_text_color = "#52514e"
+
+# surfaces — warm neutrals from the chart chrome
+background_color = "#f4f3ef"
+content_background_color = "#fcfcfb"
+surface_color = "#fcfcfb"
+sidebar_background_color = "#f4f3ef"
+sidebar_text_color = "#0b0b0b"
+border_color = "#e1e0d9"
+
+# accents — the figures' capability blue
+primary_color = "#2a78d6"
+accent_color = "#2a78d6"
+focus_border_color = "#2a78d6"
+topbar_background_color = "#0b0b0b"
+topbar_text_color = "#fcfcfb"