feat(sync): validate negentropy event receipt and retry missing events

Add validation that all events requested by ID during negentropy sync
are actually received from the relay. When events are missing:

- Log detailed information (requested/received/missing counts and IDs)
- Create retry subscriptions for missing events (chunked by 300)
- Update batch to track only missing events in next round
- Only complete batch after all events received or retry fails

This handles relays that have limits on ID-based queries (e.g., max 150
events per query) by automatically retrying in smaller chunks.

Also excludes purgatory and rejected announcement events from negentropy
requests to avoid re-requesting events we know we can't/won't store.

Note: Current implementation lacks retry limit - infinite loop protection
needed (tracked as future work).

1 files changed, 4 insertions, 0 deletions

diff --git a/src/sync/algorithms.rs b/src/sync/algorithms.rs
index f4b1f5c..4679986 100644
--- a/src/sync/algorithms.rs
+++ b/src/sync/algorithms.rs
@@ -402,6 +402,8 @@ mod tests {
                 outstanding_subs: HashSet::new(),
                 sync_method: SyncMethod::ReqEose,
                 pagination_state: HashMap::new(),
+                requested_event_ids: None,
+                received_event_ids: None,
             }],
         );
 
@@ -514,6 +516,8 @@ mod tests {
                 outstanding_subs: HashSet::new(),
                 sync_method: SyncMethod::ReqEose,
                 pagination_state: HashMap::new(),
+                requested_event_ids: None,
+                received_event_ids: None,
             }],
         );