Implement distributed synchronization features

- Added a sync manager to handle distributed synchronization across relay peers, initialized in the main application run function.
- Enhanced the event handling to update the serial number for synchronization when events are processed.
- Introduced new API endpoints for synchronization, allowing peers to fetch the current serial number and events within a specified range.
- Implemented peer request validation for synchronization endpoints to ensure authorized access based on NIP-98 authentication.
- Updated configuration to support relay peers for synchronization.
- Bumped version to v0.24.0 to reflect these changes.

app/main.go

@@ -20,6 +20,7 @@ import (
 	"next.orly.dev/pkg/policy"
 	"next.orly.dev/pkg/protocol/publish"
 	"next.orly.dev/pkg/spider"
+	dsync "next.orly.dev/pkg/sync"
 )
 
 func Run(
@@ -116,6 +117,27 @@ func Run(
 		}
 	}
 
+	// Initialize sync manager if relay peers are configured
+	if len(cfg.RelayPeers) > 0 {
+		// Get relay identity for node ID
+		sk, err := db.GetOrCreateRelayIdentitySecret()
+		if err != nil {
+			log.E.F("failed to get relay identity for sync: %v", err)
+		} else {
+			nodeID, err := keys.SecretBytesToPubKeyHex(sk)
+			if err != nil {
+				log.E.F("failed to derive pubkey for sync node ID: %v", err)
+			} else {
+				relayURL := cfg.RelayURL
+				if relayURL == "" {
+					relayURL = fmt.Sprintf("http://localhost:%d", cfg.Port)
+				}
+				l.syncManager = dsync.NewManager(ctx, db, nodeID, relayURL, cfg.RelayPeers)
+				log.I.F("distributed sync manager initialized with %d peers", len(cfg.RelayPeers))
+			}
+		}
+	}
+
 	// Initialize the user interface
 	l.UserInterface()