feat: add demo space auth bypass in middleware

Skip EncryptID token check for demo subdomains when
ENCRYPTID_DEMO_SPACES env var is set. Uses isDemoRequest()
from @encryptid/sdk v0.2.0.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

middleware.ts

@@ -1,5 +1,6 @@
 import { NextResponse } from 'next/server'
 import type { NextRequest } from 'next/server'
+import { isDemoRequest } from '@encryptid/sdk/server/nextjs'
 
 /**
  * Middleware to protect /space routes.
@@ -9,15 +10,18 @@ import type { NextRequest } from 'next/server'
  * requests — if no encryptid_token cookie is present on /space, redirect to
  * the home page with a login hint.
  *
- * Note: Since rfunds uses client-side Zustand persistence (localStorage),
- * the primary auth gate is in the SpacePage component itself. This middleware
- * serves as an additional layer for direct URL access.
+ * Demo spaces (ENCRYPTID_DEMO_SPACES env var) bypass auth.
  */
 export function middleware(request: NextRequest) {
   const { pathname } = request.nextUrl
 
   // Only protect /space routes (not /tbff which is a public demo)
   if (pathname.startsWith('/space')) {
+    // Demo spaces get anonymous access — SDK provides synthetic claims
+    if (isDemoRequest(request)) {
+      return NextResponse.next()
+    }
+
     // Check for auth token in cookie (set by client after login)
     const token = request.cookies.get('encryptid_token')?.value
 
@@ -26,9 +30,6 @@ export function middleware(request: NextRequest) {
     const bearerToken = authHeader?.startsWith('Bearer ') ? authHeader.slice(7) : null
 
     if (!token && !bearerToken) {
-      // No auth — redirect to home with login hint
-      // The client-side auth store is the primary gate, but this catches
-      // direct navigation before hydration
       const url = request.nextUrl.clone()
       url.pathname = '/'
       url.searchParams.set('login', 'required')