feat(feedback): render links in the operator reply (open in a new tab)

Linkify the operator reply on the feedback screen: http/https/ftp/mailto/tel URLs
become anchors (target=_blank rel=noopener), everything else stays escaped text.
A small whitelisted regex (no dependency) — the reply is operator-authored, so
explicit schemes suffice; dangerous schemes (javascript:/data:) are never linked,
and \b avoids matching a scheme inside a word (hotel:, email:).

ui/src/lib/mock/client.ts

@@ -435,7 +435,7 @@ export class MockGateway implements GatewayClient {
   // mockAdminReply simulates an operator reply: it clears the pending message, sets the
   // reply and raises the badge via a live admin_reply notification. e2e hook:
   // window.__mock.adminReply.
-  mockAdminReply(body = 'Thanks — we are looking into it.'): void {
+  mockAdminReply(body = 'Thanks — see https://example.com/help for details.'): void {
     this.feedbackPending = false;
     this.feedbackReply = { body, repliedAtUnix: Math.floor(Date.now() / 1000) };
     this.feedbackReplyUnread = true;