fix(auth): avoid stale redirects after auth changes

Use full-page navigation after login/logout so the dashboard reloads
with the fresh auth cookie, and mark login/logout responses no-store.

Fixes #2100

Co-authored-by: Cursor <cursoragent@cursor.com>

src/app/api/auth/logout/route.js

@@ -8,5 +8,5 @@ export async function POST() {
   cookieStore.delete("oidc_state");
   cookieStore.delete("oidc_nonce");
   cookieStore.delete("oidc_code_verifier");
-  return NextResponse.json({ success: true });
+  return NextResponse.json({ success: true }, { headers: { "Cache-Control": "no-store" } });
 }