feat: announcement purgatory

Extends purgatory to hold repository announcements until git data arrives,
preventing empty repositories from being served to clients.

When an announcement is received, a bare repo is created immediately and the
announcement is held in purgatory. It is only promoted and served once a git
push confirms real content exists. If no push arrives before expiry, the bare
repo is deleted and the announcement is silently discarded.

Key behaviours:
- Soft expiry: announcements are hidden from clients but kept alive while git
  pushes are in progress, reviving on successful push
- Expiry is extended when a matching state event or git push is observed
- NIP-09 deletion events remove announcements from purgatory
- Purgatory state (announcements, state events, PR events, expired set) is
  persisted to disk on graceful shutdown and restored on startup, with elapsed
  downtime subtracted from expiry deadlines
- Purgatory announcements drive StateOnly sync in the sync system so state
  events are fetched from listed relays before promotion
- SyncLevel added to RepoSyncIndex to distinguish purgatory repos (StateOnly)
  from promoted repos (Full L2+L3 sync)

1 files changed, 11 insertions, 21 deletions

diff --git a/tests/sync/historic_sync.rs b/tests/sync/historic_sync.rs
index aec2819..723b776 100644
--- a/tests/sync/historic_sync.rs
+++ b/tests/sync/historic_sync.rs
@@ -224,34 +224,24 @@ async fn test_history_sync_without_negentropy() {
     // Create keys
     let keys = Keys::generate();
 
-    // Create announcement listing BOTH relay domains
-    // This event will exist on source BEFORE syncing relay ever connects
-    let announcement = create_repo_announcement(
+    // Set up announcement on source with git data
+    // (purgatory requires git data before announcements are accepted)
+    let domains = vec![source.domain(), syncing_domain.clone()];
+    let domain_refs: Vec<&str> = domains.iter().map(|s| s.as_str()).collect();
+    let (announcement, _git_dir) = setup_announcement_on_relay(
+        &source,
         &keys,
-        &[&source.domain(), &syncing_domain],
+        &domain_refs,
         "test-repo-history-no-negentropy",
-    );
+    )
+    .await;
     let announcement_id = announcement.id;
 
     println!(
-        "Created announcement {} (kind {})",
-        announcement_id,
-        announcement.kind.as_u16()
+        "Announcement {} set up on source with git data (event exists BEFORE syncing relay connects)",
+        announcement_id
     );
 
-    // Send announcement to source (event now exists BEFORE syncing relay connects)
-    let client = TestClient::new(source.url(), keys.clone())
-        .await
-        .expect("Failed to connect to source");
-
-    client
-        .send_event(&announcement)
-        .await
-        .expect("Failed to send announcement to source");
-    println!("Announcement sent to source (event exists BEFORE syncing relay connects)");
-
-    client.disconnect().await;
-
     // Wait to ensure event is stored
     tokio::time::sleep(Duration::from_millis(500)).await;