fix: replace repo_sync_index wiring with purgatory announcement sync timer

Instead of threading repo_sync_index through PolicyContext/builder.rs/main.rs
to handle user-submitted purgatory announcements, add a simple background
timer (run_purgatory_announcement_sync, every 5s) that scans the purgatory
for announcement entries and registers them in repo_sync_index as StateOnly.

This is simpler and covers both flows:
- Sync-path announcements: inline registration still happens during event
  processing (sync/mod.rs:1839+), timer provides a safety net
- User-submitted announcements: SelfSubscriber never sees them (rejected
  from DB), timer is the primary registration path

The timer calls sync_purgatory_announcements_to_index() which:
1. Snapshots purgatory via new announcements_for_sync() public method
2. Or_inserts StateOnly entries (never downgrades Full entries)
3. Detects newly added relay URLs and calls handle_new_sync_filters to
   connect and subscribe - fixing the failing test that expected relay
   discovery from a user-submitted purgatory announcement

Removes: repo_sync_index field from PolicyContext, set/get_repo_sync_index
methods, set_repo_sync_index on Nip34WritePolicy, wiring in main.rs, and
the inline AcceptPurgatory registration block in builder.rs.

1 files changed, 0 insertions, 7 deletions

diff --git a/src/main.rs b/src/main.rs
index ebe05a3..ab6ede7 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -132,13 +132,6 @@ async fn main() -> Result<()> {
         // Get a reference to the rejected events index for shutdown persistence
         let shutdown_rejected_index = sync_manager.rejected_events_index();
 
-        // Wire repo_sync_index into write policy so user-submitted purgatory announcements
-        // get registered for state event sync immediately (Fix 3).
-        let repo_sync_index = sync_manager.repo_sync_index();
-        relay_with_db
-            .write_policy
-            .set_repo_sync_index(repo_sync_index);
-
         tokio::spawn(async move {
             sync_manager.run().await;
         });