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/config.toml

@@ -0,0 +1,79 @@
+# Mercury app-shell theme — NTT DATA brand (light), modern surfaces.
+# See docs/brand.md for the source palette. Loaded from the directory where
+# you launch `mercury` (this study root); restart the server to apply.
+
+[main]
+title = "CX Discovery Workshop"
+favicon_emoji = "🧭"
+footer = "CX Exploration & Discovery Workshop · NTT DATA"
+notebooks_button_label = "Workshops"
+
+[welcome]
+header = "CX Discovery Workshop"
+message = """
+The live visual for a CX exploration & discovery session — open
+**cx_discovery.ipynb**. Topics and progress render on screen for the
+client; the facilitator drives the question script and captures notes
+backstage. Mark each topic's status in the sidebar as the conversation
+moves — the board and the progress bar update live. Afterward, export the
+captured notes for drafting with `python scripts/export_report.py`.
+"""
+
+[theme]
+# ── Type — Georgia headings, Arial body (web-safe; no network fetch). ──
+font_family         = "Arial, 'Helvetica Neue', Helvetica, sans-serif"
+heading_font_family = "Georgia, 'Times New Roman', Times, serif"
+font_size           = "15px"
+font_weight         = "normal"
+heading_font_weight = "700"
+
+# ── Text — NTT ink scale ──
+text_color       = "#2e404d"
+muted_text_color = "#586671"
+
+# ── Surfaces — white content on a soft neutral canvas ──
+background_color         = "#f4f5f6"
+content_background_color = "#ffffff"
+surface_color            = "#ffffff"
+card_background_color    = "#f8f8f8"
+border_color             = "#d5d9db"
+border_radius            = "10px"
+
+# ── Accents — Future Blue ──
+primary_color             = "#0072bc"
+accent_color              = "#0072bc"
+focus_border_color        = "#0072bc"
+hover_background_color     = "#eef5fb"
+selected_background_color = "#dcecfa"
+
+# ── State colors — brand Success / Warning / Error (docs/brand.md) ──
+success_color      = "#00cb5d"
+warning_color      = "#ffc400"
+danger_color       = "#e42600"
+slider_track_color = "#e2e6e9"
+
+# ── Sidebar — clean white, hairline divider ──
+sidebar_background_color = "#ffffff"
+sidebar_text_color       = "#2e404d"
+sidebar_title_color      = "#151d2c"
+sidebar_shadow           = "1px 0 0 #d5d9db"
+
+# ── Top bar — deep NTT navy ──
+topbar_background_color = "#151d2c"
+topbar_text_color       = "#ffffff"
+topbar_border_color     = "rgba(255,255,255,0.08)"
+
+# ── Footer ──
+footer_background_color = "#ffffff"
+footer_text_color       = "#586671"
+footer_border_color     = "#d5d9db"
+
+# ── Run button — subtle brand-blue gradient ──
+run_button_background       = "linear-gradient(180deg, #0087dc 0%, #0072bc 100%)"
+run_button_background_hover = "linear-gradient(180deg, #1a93e6 0%, #0079c8 100%)"
+run_button_text_color       = "#ffffff"
+
+# ── Depth — soft, navy-tinted shadows ──
+shadow_sm = "0 1px 2px rgba(21,29,44,0.05)"
+shadow_md = "0 6px 18px rgba(21,29,44,0.08)"
+shadow_lg = "0 16px 40px rgba(21,29,44,0.10)"