Add Compare with Resend panel to Subscribers; stop resubscribing opted-out contacts; v2.6.1

- Subscribers: compare in-app list with Resend audience/segment, with one-click fixes
- syncContactToResend no longer resets unsubscribed on existing contacts

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

package.json

@@ -1,7 +1,7 @@
 {
   "name": "siteforge",
   "private": true,
-  "version": "2.5.0",
+  "version": "2.6.1",
   "type": "module",
   "scripts": {
     "dev": "vite",