fix: NIP-01 compliance - add deterministic event ordering by event_id

For events with the same created_at timestamp, add secondary sort by event_id
in ascending order to ensure deterministic ordering as specified by NIP-01.

Fixes #477 - non-deterministic event ordering in findByFilters

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

Author: github-manager

src/repositories/event-repository.ts

@@ -122,9 +122,9 @@ export class EventRepository implements IEventRepository {
       }
 
       if (typeof currentFilter.limit === 'number') {
-        builder.limit(currentFilter.limit).orderBy('event_created_at', 'DESC')
+        builder.limit(currentFilter.limit).orderBy('event_created_at', 'DESC').orderBy('event_id', 'asc')
       } else {
-        builder.limit(500).orderBy('event_created_at', 'asc')
+        builder.limit(500).orderBy('event_created_at', 'asc').orderBy('event_id', 'asc')
       }
 
       const andWhereRaw = invoker(1, 'andWhereRaw')