Unify SHA256 hash and hex usages (#687)

bitchat/Protocols/BinaryEncodingUtils.swift

@@ -197,7 +197,7 @@ extension Data {
         offset += 16
         
         // Convert 16 bytes to UUID string format
-        let uuid = uuidData.map { String(format: "%02x", $0) }.joined()
+        let uuid = uuidData.hexEncodedString()
         
         // Insert hyphens at proper positions: 8-4-4-4-12
         var result = ""

bitchat/Protocols/PeerID.swift

@@ -1,14 +0,0 @@
-import Foundation
-import CryptoKit
-
-// MARK: - Peer ID Utilities
-
-struct PeerIDUtils {
-    /// Derive the stable 16-hex peer ID from a Noise static public key
-    static func derivePeerID(fromPublicKey publicKey: Data) -> String {
-        let digest = SHA256.hash(data: publicKey)
-        let hex = digest.map { String(format: "%02x", $0) }.joined()
-        return String(hex.prefix(16))
-    }
-}
-

bitchat/Protocols/PeerIDUtils.swift

@@ -0,0 +1,9 @@
+import Foundation
+
+struct PeerIDUtils {
+    /// Derive the stable 16-hex peer ID from a Noise static public key
+    static func derivePeerID(fromPublicKey publicKey: Data) -> String {
+        String(publicKey.sha256Fingerprint().prefix(16))
+    }
+}
+