feat: public events/polls, friends graph, captcha, SSE hardening, and admin UX

Ship product gaps: register/vote pages, friend add/accept/decline/remove, email verify TTL, captcha on login/forgot, soft-fail user actions, SSE abort/shared client, Commando Centrum error toasts, admin delete for events/polls, and IT/NL i18n fills.

Co-authored-by: Cursor <[email protected]>

src/app/api/admin/import/clone/sync-all/route.ts

@@ -95,6 +95,7 @@ export const POST = withAdmin(
 		return runSseBatch({
 			items: allItems,
 			concurrency: 2,
+			signal: request.signal,
 			labelOf: (it) => `${it.sourceName}/${it.classname}`,
 			worker: async (it, _index, report) => {
 				const allSrc = await listSources();