feat: implement NIP-09 (deletions) and NIP-11 (relay info)

NIP-11 (Relay Information Document):
- Serves relay metadata at GET / with Accept: application/nostr+json
- Returns name, description, supported NIPs, limitations
- CORS headers for browser compatibility

NIP-09 (Event Deletion):
- Kind 5 events delete events referenced in 'e' tags
- Only authors can delete their own events
- Soft delete (marks deleted=1)
- Records deletion in deletions table
- Works across all protocols (gRPC, Connect, WebSocket)

Fixed deletions schema:
- deleted_event_id as PRIMARY KEY (not deletion_event_id)
- Allows one deletion event to delete multiple events

3 new tests, 44 total tests passing

Supported NIPs now: 1, 9, 11

1 files changed, 2 insertions, 0 deletions

diff --git a/README.md b/README.md
index 35e697c..d2fbd41 100644
--- a/README.md
+++ b/README.md
@@ -100,6 +100,8 @@ See [proto/nostr/v1/nostr.proto](proto/nostr/v1/nostr.proto) for the full API.
   - **WebSocket** (NIP-01 - standard Nostr protocol)
 - ✅ Subscribe/streaming (real-time event delivery)
 - ✅ Subscription management (filter matching, fan-out)
+- ✅ **NIP-09** - Event deletion (authors can delete their own events)
+- ✅ **NIP-11** - Relay info document (GET with `Accept: application/nostr+json`)
 
 **Compatible with:**
 - Any gRPC client (Go, Python, JS, etc.)