Perf: Add final to classes that are not inherited (#574)

bitchat/Noise/NoiseHandshakeCoordinator.swift

@@ -9,7 +9,7 @@
 import Foundation
 
 /// Coordinates Noise handshakes to prevent race conditions and ensure reliable encryption establishment
-class NoiseHandshakeCoordinator {
+final class NoiseHandshakeCoordinator {
     
     // MARK: - Handshake State
     

bitchat/Noise/NoiseProtocol.swift

@@ -127,7 +127,7 @@ struct NoiseProtocolName {
 /// Handles ChaCha20-Poly1305 AEAD encryption with automatic nonce management
 /// and replay protection using a sliding window algorithm.
 /// - Warning: Nonce reuse would be catastrophic for security
-class NoiseCipherState {
+final class NoiseCipherState {
     // Constants for replay protection
     private static let NONCE_SIZE_BYTES = 4
     private static let REPLAY_WINDOW_SIZE = 1024
@@ -384,7 +384,7 @@ class NoiseCipherState {
 /// Responsible for key derivation, protocol name hashing, and maintaining
 /// the chaining key that provides key separation between handshake messages.
 /// - Note: This class implements the SymmetricState object from the Noise spec
-class NoiseSymmetricState {
+final class NoiseSymmetricState {
     private var cipherState: NoiseCipherState
     private var chainingKey: Data
     private var hash: Data
@@ -488,7 +488,7 @@ class NoiseSymmetricState {
 /// This is the main interface for establishing encrypted sessions between peers.
 /// Manages the handshake state machine, message patterns, and key derivation.
 /// - Important: Each handshake instance should only be used once
-class NoiseHandshakeState {
+final class NoiseHandshakeState {
     private let role: NoiseRole
     private let pattern: NoisePattern
     private var symmetricState: NoiseSymmetricState

bitchat/Noise/NoiseSecurityConsiderations.swift

@@ -61,7 +61,7 @@ struct NoiseSecurityValidator {
 
 // MARK: - Enhanced Noise Session with Security
 
-class SecureNoiseSession: NoiseSession {
+final class SecureNoiseSession: NoiseSession {
     private(set) var messageCount: UInt64 = 0
     private let sessionStartTime = Date()
     private(set) var lastActivityTime = Date()
@@ -135,7 +135,7 @@ class SecureNoiseSession: NoiseSession {
 
 // MARK: - Rate Limiter
 
-class NoiseRateLimiter {
+final class NoiseRateLimiter {
     private var handshakeTimestamps: [String: [Date]] = [:] // peerID -> timestamps
     private var messageTimestamps: [String: [Date]] = [:] // peerID -> timestamps
     

bitchat/Noise/NoiseSession.swift

@@ -250,7 +250,7 @@ class NoiseSession {
 
 // MARK: - Session Manager
 
-class NoiseSessionManager {
+final class NoiseSessionManager {
     private var sessions: [String: NoiseSession] = [:]
     private let localStaticKey: Curve25519.KeyAgreement.PrivateKey
     private let managerQueue = DispatchQueue(label: "chat.bitchat.noise.manager", attributes: .concurrent)