fix(web-admin): add Next.js proxy route for /api/app/version/check

Fixes QR code not showing on my-org and register pages.

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

it0-web-admin/src/app/api/app/version/check/route.ts

@@ -0,0 +1,16 @@
+import { NextRequest, NextResponse } from 'next/server';
+
+function getApiBaseUrl(): string {
+  return process.env.API_BASE_URL || 'http://localhost:8000';
+}
+
+export async function GET(request: NextRequest) {
+  const url = `${getApiBaseUrl()}/api/app/version/check${request.nextUrl.search}`;
+  try {
+    const res = await fetch(url, { cache: 'no-store' });
+    const data = await res.json();
+    return NextResponse.json(data, { status: res.status });
+  } catch {
+    return NextResponse.json({ error: 'version service unavailable' }, { status: 503 });
+  }
+}