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).

0 files changed, 0 insertions, 0 deletions