feat: remove purgatory announcements on NIP-09 deletion events

Kind 5 deletion events signed by the announcement author now evict the
corresponding purgatory entry and delete the bare repository from disk.

Both NIP-09 reference styles are supported:
- e tag (event ID): matches the purgatory entry whose event ID equals the tag value
- a tag (coordinate 30617:<pubkey>:<identifier>): matches by coordinate, only
  removes entries with created_at <= deletion event created_at per NIP-09 spec

Author-only enforcement: coordinate pubkey and e-tag owner must match the
deletion event pubkey; third-party deletion attempts are silently ignored.

Includes 6 unit tests and 2 integration tests (event ID and coordinate paths).

1 files changed, 7 insertions, 0 deletions

diff --git a/tests/purgatory.rs b/tests/purgatory.rs
index efc28c9..553271f 100644
--- a/tests/purgatory.rs
+++ b/tests/purgatory.rs
@@ -67,6 +67,13 @@ isolated_purgatory_test!(test_bare_repo_exists_for_purgatory_announcement);
 isolated_purgatory_test!(test_state_event_accepted_for_purgatory_announcement);
 
 // ============================================================
+// Deletion Event Tests (NIP-09)
+// ============================================================
+
+isolated_purgatory_test!(test_deletion_by_event_id_removes_purgatory_announcement);
+isolated_purgatory_test!(test_deletion_by_coordinate_removes_purgatory_announcement);
+
+// ============================================================
 // State Event Purgatory Tests (already implemented)
 // ============================================================