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/components.json

@@ -0,0 +1,25 @@
+{
+  "$schema": "https://ui.shadcn.com/schema.json",
+  "style": "radix-nova",
+  "rsc": false,
+  "tsx": true,
+  "tailwind": {
+    "config": "",
+    "css": "src/index.css",
+    "baseColor": "neutral",
+    "cssVariables": true,
+    "prefix": ""
+  },
+  "iconLibrary": "lucide",
+  "rtl": false,
+  "aliases": {
+    "components": "@/components",
+    "utils": "@/lib/utils",
+    "ui": "@/components/ui",
+    "lib": "@/lib",
+    "hooks": "@/hooks"
+  },
+  "menuColor": "default",
+  "menuAccent": "subtle",
+  "registries": {}
+}