M1 UI: shadcn + TeamUp design language

Initialize shadcn/ui (radix-nova, Tailwind v4) in client/ and rebuild the M1 interface
on the design language:
- Token layer recolored in index.css: light "calm command center" content surface,
  rationed indigo brand, the deep-indigo sidebar, the load-bearing seat-state triad
  (--color-seat-human slate / -open amber / -ai indigo) + teal "approved" / amber "held",
  Hanken Grotesk (variable) as the production font.
- App shell: deep-indigo sidebar (Board / Cartable / Org-chart-soon nav + sign out) on a
  light content area; StatusDot uses the seat-state tokens.
- LoginPage: Card-based sign-in / first-owner bootstrap, toast (sonner) errors.
- BoardPage: shadcn Card columns (backlog→in progress→in review→done), Badge task types,
  Select to move, Avatar/Assign-to-me, and the cartable panel — wired to the M1 API.
- Path alias @ -> src (tsconfig paths + vite); dropped baseUrl (deprecated in TS 6).

Components added via the shadcn CLI: button, card, badge, input, label, select,
separator, avatar, skeleton, sonner. Client `npm run build` is green (tsc + vite).
Still pending a live click-through.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

client/package.json

@@ -11,14 +11,25 @@
   },
   "dependencies": {
     "@dnd-kit/core": "^6.3.1",
+    "@fontsource-variable/geist": "^5.2.9",
+    "@fontsource-variable/hanken-grotesk": "^5.2.8",
     "@hookform/resolvers": "^5.4.0",
     "@tanstack/react-query": "^5.101.0",
     "@xyflow/react": "^12.11.0",
+    "class-variance-authority": "^0.7.1",
+    "clsx": "^2.1.1",
+    "lucide-react": "^1.17.0",
+    "next-themes": "^0.4.6",
+    "radix-ui": "^1.5.0",
     "react": "^19.2.6",
     "react-dom": "^19.2.6",
     "react-hook-form": "^7.78.0",
     "react-router": "^7.17.0",
     "recharts": "^3.8.1",
+    "shadcn": "^4.11.0",
+    "sonner": "^2.0.7",
+    "tailwind-merge": "^3.6.0",
+    "tw-animate-css": "^1.4.0",
     "zod": "^4.4.3",
     "zustand": "^5.0.14"
   },