docs: introduce Mercury Notebook Deliverable Pattern

template/MercuryNotebook/README.md

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+# Mercury Notebook Template
+
+Copy-me starting point for a Palladium study, per
+[`docs/Mercury_Notebook_Pattern_V1-00.md`](../../docs/Mercury_Notebook_Pattern_V1-00.md).
+The toy model is complete on purpose — every pattern mechanism (verbatim
+anchor + contracted overlay, ramp mechanics, baseline-relative frame,
+widget-pair reactivity, verification gate, backstage appendix, exports)
+is present and runnable, so you replace math, not plumbing.
+
+## Start a study
+
+```bash
+cp -r template/MercuryNotebook studies/YYYYMM_Client_EngagementName
+cd studies/YYYYMM_Client_EngagementName
+# 1. Rename the package (underscores only — dashes break Python imports):
+#    studylib/ → <yourstudy>lib/, then fix pyproject.toml + imports.
+# 2. Replace studylib/model.py's toy domain with your math;
+#    re-pin tests/test_model.py with hand-checked numbers.
+# 3. Rework notebooks/business_case.ipynb section by section —
+#    keep the widget-pair cells, gate cell, and appendix cell structure.
+pip install -e ".[dev]"
+```
+
+## Run
+
+| Task | Command |
+|---|---|
+| Tests | `pytest` |
+| Serve (the stage) | `mercury --working-dir notebooks/` (run from project root so `config.toml` loads) |
+| Analyst view (backstage) | `jupyter lab` |
+| Headless check | `jupyter nbconvert --to notebook --execute --inplace notebooks/business_case.ipynb` |
+| Export for LLMs | `python scripts/export_report.py` |
+
+## What's here
+
+```
+studylib/model.py      # ALL math — notebooks hold none
+studylib/staging.py    # on_stage()/backstage() — Mercury vs JupyterLab/nbconvert
+notebooks/business_case.ipynb
+scripts/export_report.py
+tests/                 # hand-checked pinned acceptance numbers
+config.toml            # Mercury theme (NTT DATA brand)
+pyproject.toml         # full toolchain as core deps — no requirements.txt
+```
+
+Reference implementation (a full multi-notebook study):
+`studies/202512_GenesysCX/ctm-token-calculator/`.