Submissions persistence: publish to nos.lol + admin re-broadcast mirror

Submissions are signed by throwaway ephemeral keys and public relays prune
events from pubkeys with no social graph, so the queue quietly evaporated.

- Forms: also publish to nos.lol (better retention, already in the app's
  query set) alongside snort/damus/primal.
- submissionFacade: on each fetch, re-broadcast the still-pending signed
  events back to our relays (publishEventToRelays) so pruning doesn't drop
  them. Best-effort, fire-and-forget — never blocks or fails the fetch;
  no-ops when no relay pool is available.
- test: fetch still returns the pending queue when a pool is present.

Co-Authored-By: Claude Opus 4.8 <[email protected]>

components/iframe_forms/iframe-feedback-form.html

@@ -202,6 +202,7 @@
           "wss://relay.snort.social",
           "wss://relay.damus.io",
           "wss://relay.primal.net",
+          "wss://nos.lol",
         ];
         const pool = new SimplePool();