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, 2 insertions, 0 deletions

diff --git a/src/nostr/policy/mod.rs b/src/nostr/policy/mod.rs
index 1566b6c..f5b981a 100644
--- a/src/nostr/policy/mod.rs
+++ b/src/nostr/policy/mod.rs
@@ -6,11 +6,13 @@
 /// - `PrEventPolicy` - PR/PR Update validation
 /// - `RelatedEventPolicy` - Forward/backward reference checking
 mod announcement;
+mod deletion;
 mod pr_event;
 mod related;
 mod state;
 
 pub use announcement::{AnnouncementPolicy, AnnouncementResult};
+pub use deletion::DeletionPolicy;
 pub use pr_event::PrEventPolicy;
 pub use related::{ReferenceResult, RelatedEventPolicy};
 pub use state::{StatePolicy, StateResult};