Paginate and add search to the newsletter signups endpoint

Unlike guest book and free-text, newsletter signups had no LIMIT at all and the frontend rendered every row in one plain table. Newsletter opt-in is a single checkbox rather than typed text, so it's plausibly the largest per-event list - fix it the same way as guest book: paginated (page/pageSize, capped at 200/page) plus an optional ?search= over first name, last name, and email.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/models/feedback/admin/reports.admin.router.ts

@@ -110,7 +110,7 @@ reportsAdminRouter.get('/:eventId/guestbook', async (req: Request, res: Response
  * /feedback/admin/events/{eventId}/newsletter:
  *      get:
  *          summary: Newsletter signups for one event
- *          description: Includes sync_status, so failures can be handled manually.
+ *          description: Includes sync_status, so failures can be handled manually. Newest first, paginated.
  *          tags: [feedback-admin]
  *          parameters:
  *              - $ref: '#/components/parameters/SessionIdHeader'
@@ -120,6 +120,19 @@ reportsAdminRouter.get('/:eventId/guestbook', async (req: Request, res: Response
  *                required: true
  *                schema:
  *                    type: integer
+ *              - in: query
+ *                name: page
+ *                schema:
+ *                    type: integer
+ *              - in: query
+ *                name: pageSize
+ *                schema:
+ *                    type: integer
+ *              - in: query
+ *                name: search
+ *                description: Filters entries whose first name, last name, or email contains this text (case-insensitive).
+ *                schema:
+ *                    type: string
  *          responses:
  *              200:
  *                  description: Success
@@ -128,7 +141,11 @@ reportsAdminRouter.get('/:eventId/guestbook', async (req: Request, res: Response
  */
 reportsAdminRouter.get('/:eventId/newsletter', async (req: Request, res: Response) => {
 	try {
-		res.status(200).send(await ReportsAdminService.getNewsletterSignups(Number(req.params.eventId)));
+		const page = Math.max(1, Number(req.query.page) || 1);
+		const pageSize = Math.min(200, Math.max(1, Number(req.query.pageSize) || 50));
+		const search = typeof req.query.search === 'string' ? req.query.search : undefined;
+		const result = await ReportsAdminService.getNewsletterSignups(Number(req.params.eventId), page, pageSize, search);
+		res.status(200).send(result);
 	} catch (e: any) {
 		sendServerError(res, e);
 	}