Reuse an existing session instead of recreating

bitchat/Noise/NoiseSessionManager.swift

@@ -60,23 +60,24 @@ final class NoiseSessionManager {
                 throw NoiseSessionError.alreadyEstablished
             }
             
-            // Remove any existing non-established session
+            let session: NoiseSession
-            if let existingSession = sessions[peerID], !existingSession.isEstablished() {
-                _ = sessions.removeValue(forKey: peerID)
-            }
             
+            if let existingSession = sessions[peerID] {
+                session = existingSession
+                session.reset()
+            } else {
                 // Create new initiator session
-            let session = SecureNoiseSession(
+                session = SecureNoiseSession(
                     peerID: peerID,
                     role: .initiator,
                     keychain: keychain,
                     localStaticKey: localStaticKey
                 )
                 sessions[peerID] = session
+            }
             
             do {
-                let handshakeData = try session.startHandshake()
+                return try session.startHandshake()
-                return handshakeData
             } catch {
                 // Clean up failed session
                 _ = sessions.removeValue(forKey: peerID)