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_AI_Diagnostic/scripts/export_report.py

@@ -0,0 +1,47 @@
+"""Export the deliverable notebook as LLM-readable report sources.
+
+Executes the notebook fresh (widget seeds — the mock scenario, or
+whatever seeds you edit in), then writes both formats to exports/:
+
+  exports/diagnostic.html  — human-reviewable, tables render
+  exports/diagnostic.md    — leanest LLM input
+
+Plotly figures export as JavaScript an LLM cannot read; the notebook's
+machine-readable appendix section carries every number behind them.
+
+Run from the project root:  python scripts/export_report.py [name-filter]
+An optional argument exports only notebooks whose filename contains it.
+"""
+from __future__ import annotations
+
+import subprocess
+import sys
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parent.parent
+NOTEBOOKS = [
+    ROOT / "notebooks" / "diagnostic.ipynb",
+]
+EXPORTS = ROOT / "exports"
+
+
+def main() -> None:
+    picked = [nb for nb in NOTEBOOKS
+              if len(sys.argv) < 2 or sys.argv[1] in nb.name]
+    if not picked:
+        sys.exit(f"no notebook matches {sys.argv[1]!r}")
+    EXPORTS.mkdir(exist_ok=True)
+    for nb in picked:
+        for fmt in ("html", "markdown"):
+            subprocess.run(
+                [sys.executable, "-m", "nbconvert", "--execute",
+                 "--to", fmt, "--output-dir", str(EXPORTS), str(nb)],
+                check=True, cwd=ROOT,
+            )
+    for p in sorted(EXPORTS.iterdir()):
+        if p.suffix in (".html", ".md"):
+            print(f"wrote {p.relative_to(ROOT)} ({p.stat().st_size / 1024:,.0f} KB)")
+
+
+if __name__ == "__main__":
+    main()