fix: deliver events to every matching subscription on a connection

notify_event returned after the first filter that matched, so a
connection holding several subscriptions only ever received an event on
one of them. That is invisible with one subscription per client, but a
multiplexer such as nostrclient funnels all of its clients through a
single connection. With nwcprovider subscribed to its own kind-23195
responses, every NWC reply was handed to that subscription and stopped
there; the wallet app's subscription on the same connection never saw
it, and Amethyst reported "wallet request timed out". Direct to the
relay it worked, because the app then had its own connection.

Deliver once per subscription id instead, and demote the per-filter
miss log to debug: it emitted one INFO line per filter per event.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013Tbyw6FwjhEJg3gHfPHxWt

relay/client_connection.py

@@ -72,16 +72,24 @@ class NostrClientConnection:
         if self._is_private_event_for_other(event):
             return False
 
+        # One connection can hold several subscriptions whose filters all match
+        # the same event: a multiplexer such as nostrclient funnels every one of
+        # its clients through a single connection. NIP-01 requires the event to
+        # reach each matching subscription, so deliver once per subscription id
+        # rather than stopping at the first hit.
+        notified: set[str] = set()
         for nostr_filter in self.filters:
+            sub_id = nostr_filter.subscription_id
+            if sub_id in notified:
+                continue
             if nostr_filter.matches(event):
-                resp = event.serialize_response(nostr_filter.subscription_id)
-                await self._send_msg(resp)
-                return True
+                notified.add(sub_id)  # type: ignore[arg-type]
+                await self._send_msg(event.serialize_response(sub_id))
             else:
-                logger.info(
+                logger.debug(
                     f"[NOSTRRELAY CLIENT] ❌ Filter didn't match for event {event.id}"
                 )
-        return False
+        return len(notified) > 0
 
     def _is_private_event_for_other(self, event: NostrEvent) -> bool:
         """