feat(ST-1136): mobile Settings-pagina + LogoutButton (T-325/T-326/T-327)

- app/(mobile)/m/settings/page.tsx — read-only account-info, product-selector
  (hergebruikt ActivateProductButton + setActiveProductAction met redirectTo
  /m/products/[id]/solo), QR-pairing-instructie, logout
- components/mobile/logout-button.tsx — AlertDialog "Uitloggen?" met bevestig
  + annuleer; demo-user mag uitloggen (geen demo-block)
- Tests: LogoutButton render + open + bevestig (logoutAction) + annuleer

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

components/mobile/logout-button.tsx

@@ -0,0 +1,56 @@
+'use client'
+
+import { useState, useTransition } from 'react'
+import { LogOut } from 'lucide-react'
+import {
+  AlertDialog,
+  AlertDialogAction,
+  AlertDialogCancel,
+  AlertDialogContent,
+  AlertDialogDescription,
+  AlertDialogFooter,
+  AlertDialogHeader,
+  AlertDialogTitle,
+} from '@/components/ui/alert-dialog'
+import { Button } from '@/components/ui/button'
+import { logoutAction } from '@/actions/auth'
+
+export function LogoutButton() {
+  const [open, setOpen] = useState(false)
+  const [pending, startTransition] = useTransition()
+
+  function confirm() {
+    startTransition(async () => {
+      await logoutAction()
+    })
+  }
+
+  return (
+    <>
+      <Button
+        variant="outline"
+        onClick={() => setOpen(true)}
+        className="w-full justify-center gap-2"
+      >
+        <LogOut className="size-4" aria-hidden="true" />
+        Uitloggen
+      </Button>
+      <AlertDialog open={open} onOpenChange={setOpen}>
+        <AlertDialogContent size="sm">
+          <AlertDialogHeader>
+            <AlertDialogTitle>Uitloggen?</AlertDialogTitle>
+            <AlertDialogDescription>
+              Weet je zeker dat je wilt uitloggen?
+            </AlertDialogDescription>
+          </AlertDialogHeader>
+          <AlertDialogFooter>
+            <AlertDialogCancel onClick={() => setOpen(false)}>Annuleren</AlertDialogCancel>
+            <AlertDialogAction disabled={pending} onClick={confirm}>
+              {pending ? 'Bezig…' : 'Uitloggen'}
+            </AlertDialogAction>
+          </AlertDialogFooter>
+        </AlertDialogContent>
+      </AlertDialog>
+    </>
+  )
+}