Remove more dead code

- Remove unused loggedCryptoErrors property from BluetoothMeshService
- Remove unused error cases from NoiseEncryptionError:
  - invalidMessage (never thrown)
  - handshakeFailed(Error) (never thrown)

These were identified during deeper code analysis and are
confirmed to be unused throughout the codebase.

bitchat/Services/BluetoothMeshService.swift

@@ -79,7 +79,6 @@ class BluetoothMeshService: NSObject {
     private var activePeers: Set<String> = []  // Track all active peers
     private var peerRSSI: [String: NSNumber] = [:] // Track RSSI values for peers
     private var peripheralRSSI: [String: NSNumber] = [:] // Track RSSI by peripheral ID during discovery
-    private var loggedCryptoErrors = Set<String>()  // Track which peers we've logged crypto errors for
     
     // MARK: - Peer Identity Rotation
     // Mappings between ephemeral peer IDs and permanent fingerprints

bitchat/Services/NoiseEncryptionService.swift

@@ -466,6 +466,4 @@ struct NoiseMessage: Codable {
 enum NoiseEncryptionError: Error {
     case handshakeRequired
     case sessionNotEstablished
-    case invalidMessage
-    case handshakeFailed(Error)
 }