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/src/components/AppShell.tsx

@@ -0,0 +1,78 @@
+import type { ReactNode } from 'react'
+import { Inbox, type LucideIcon, LayoutDashboard, LogOut, Network } from 'lucide-react'
+import { Button } from '@/components/ui/button'
+import { Separator } from '@/components/ui/separator'
+import { cn } from '@/lib/utils'
+import { useAuth } from '@/store/auth'
+
+export function AppShell({ children }: { children: ReactNode }) {
+  const email = useAuth((s) => s.email)
+  const logout = useAuth((s) => s.logout)
+
+  return (
+    <div className="flex min-h-screen bg-background text-foreground">
+      <aside className="flex w-60 shrink-0 flex-col bg-sidebar text-sidebar-foreground">
+        <div className="flex items-center gap-3 px-5 py-4">
+          <span className="grid size-8 place-items-center rounded-md bg-sidebar-primary font-bold text-sidebar-primary-foreground">
+            T
+          </span>
+          <div className="leading-tight">
+            <div className="font-semibold tracking-tight">TeamUp.AI</div>
+            <div className="text-xs text-sidebar-foreground/60">command center</div>
+          </div>
+        </div>
+
+        <Separator className="bg-sidebar-border" />
+
+        <nav className="flex flex-1 flex-col gap-1 p-3">
+          <NavItem icon={LayoutDashboard} label="Board" active />
+          <NavItem icon={Inbox} label="Cartable" />
+          <NavItem icon={Network} label="Org chart" muted />
+        </nav>
+
+        <Separator className="bg-sidebar-border" />
+
+        <div className="flex items-center justify-between gap-2 p-3">
+          <span className="truncate text-xs text-sidebar-foreground/70">{email ?? 'signed in'}</span>
+          <Button
+            variant="ghost"
+            size="sm"
+            onClick={logout}
+            className="text-sidebar-foreground hover:bg-sidebar-accent hover:text-sidebar-accent-foreground"
+          >
+            <LogOut data-icon="inline-start" />
+            Sign out
+          </Button>
+        </div>
+      </aside>
+
+      <main className="flex-1 overflow-auto">{children}</main>
+    </div>
+  )
+}
+
+function NavItem({
+  icon: Icon,
+  label,
+  active,
+  muted,
+}: {
+  icon: LucideIcon
+  label: string
+  active?: boolean
+  muted?: boolean
+}) {
+  return (
+    <span
+      className={cn(
+        'flex items-center gap-3 rounded-md px-3 py-2 text-sm',
+        active ? 'bg-sidebar-accent font-medium text-sidebar-accent-foreground' : 'text-sidebar-foreground/80',
+        muted && 'opacity-50',
+      )}
+    >
+      <Icon className="size-4" />
+      {label}
+      {muted && <span className="ml-auto text-[10px] uppercase tracking-wide opacity-70">soon</span>}
+    </span>
+  )
+}