feat: add master notebook library scaffolding and review tooling

Add CLAUDE.md defining the Palladium master notebook conventions and
Red Panda Approval criteria, plus a review-notebook slash command for
LLM-driven notebook review.

Expand .gitignore to block client/engagement documents and generated
exports, keeping masters client-clean while allowing text/image sources.

Normalize slider widget numeric values from floats to integers in
notebook JSON.

assessments/CX_Discovery_Workshop/pyproject.toml

@@ -0,0 +1,36 @@
+[build-system]
+requires = ["setuptools>=68"]
+build-backend = "setuptools.build_meta"
+
+[project]
+name = "discoverylib"
+version = "0.3.0"
+description = "CX Exploration & Discovery Workshop — live facilitation aid (Mercury Notebook Pattern)"
+requires-python = ">=3.10"
+# The notebook is the deliverable (served with Mercury, exported via
+# nbconvert, tables via tabulate) — the whole toolchain is a required
+# runtime dependency, not an extra. `pip install -e .` must be enough.
+dependencies = [
+    "pandas>=2.0",
+    "plotly>=5.18",
+    "mercury>=3.2",
+    "jupyterlab>=4.0",
+    "ipywidgets>=8.0",
+    "nbconvert>=7",
+    "nbformat>=5.9",
+    "tabulate>=0.9",
+]
+
+[project.optional-dependencies]
+dev = ["pytest>=7.4", "mypy>=1.8"]
+
+[tool.setuptools.packages.find]
+include = ["discoverylib*"]
+
+[tool.pytest.ini_options]
+testpaths = ["tests"]
+addopts = "-q"
+
+[tool.mypy]
+strict = true
+packages = ["discoverylib"]