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, 60 insertions, 0 deletions

diff --git a/internal/handler/websocket/nip11.go b/internal/handler/websocket/nip11.go
new file mode 100644
index 0000000..a5bb9ca
--- /dev/null
+++ b/internal/handler/websocket/nip11.go
@@ -0,0 +1,60 @@
+package websocket
+
+import (
+        "encoding/json"
+        "net/http"
+)
+
+type RelayInfo struct {
+        Name          string   `json:"name"`
+        Description   string   `json:"description"`
+        Pubkey        string   `json:"pubkey,omitempty"`
+        Contact       string   `json:"contact,omitempty"`
+        SupportedNIPs []int    `json:"supported_nips"`
+        Software      string   `json:"software"`
+        Version       string   `json:"version"`
+        Limitation    *Limits  `json:"limitation,omitempty"`
+}
+
+type Limits struct {
+        MaxMessageLength    int  `json:"max_message_length,omitempty"`
+        MaxSubscriptions    int  `json:"max_subscriptions,omitempty"`
+        MaxFilters          int  `json:"max_filters,omitempty"`
+        MaxLimit            int  `json:"max_limit,omitempty"`
+        MaxSubidLength      int  `json:"max_subid_length,omitempty"`
+        MaxEventTags        int  `json:"max_event_tags,omitempty"`
+        MaxContentLength    int  `json:"max_content_length,omitempty"`
+        MinPowDifficulty    int  `json:"min_pow_difficulty,omitempty"`
+        AuthRequired        bool `json:"auth_required"`
+        PaymentRequired     bool `json:"payment_required"`
+        RestrictedWrites    bool `json:"restricted_writes"`
+}
+
+func (h *Handler) ServeNIP11(w http.ResponseWriter, r *http.Request) {
+        info := RelayInfo{
+                Name:          "nostr-grpc relay",
+                Description:   "High-performance Nostr relay with gRPC, Connect, and WebSocket support",
+                SupportedNIPs: []int{1, 9, 11},
+                Software:      "northwest.io/nostr-grpc",
+                Version:       "0.1.0",
+                Limitation: &Limits{
+                        MaxMessageLength: 65536,
+                        MaxSubscriptions: 20,
+                        MaxFilters:       10,
+                        MaxLimit:         5000,
+                        MaxSubidLength:   64,
+                        MaxEventTags:     2000,
+                        MaxContentLength: 65536,
+                        AuthRequired:     false,
+                        PaymentRequired:  false,
+                        RestrictedWrites: false,
+                },
+        }
+
+        w.Header().Set("Content-Type", "application/nostr+json")
+        w.Header().Set("Access-Control-Allow-Origin", "*")
+        w.Header().Set("Access-Control-Allow-Headers", "Content-Type, Accept")
+        w.Header().Set("Access-Control-Allow-Methods", "GET")
+
+        json.NewEncoder(w).Encode(info)
+}