Adds O(1) method for peer nickname retrieval (#450)

* Adds O(1) method for peerNickname retrieval

* Uses peerNickname method where possible

bitchat/Services/BLEService.swift

@@ -336,7 +336,14 @@ final class BLEService: NSObject {
         }()
         return collectionsQueue.sync { peers[shortID]?.isConnected ?? false }
     }
-    
+
+    func peerNickname(peerID: String) -> String? {
+        collectionsQueue.sync {
+            guard let peer = peers[peerID], peer.isConnected else { return nil }
+            return peer.nickname
+        }
+    }
+
     func getPeerNicknames() -> [String: String] {
         return collectionsQueue.sync {
             Dictionary(uniqueKeysWithValues: peers.compactMap { (id, info) in

bitchat/Services/CommandProcessor.swift

@@ -119,7 +119,7 @@ class CommandProcessor {
         
         if chatViewModel?.selectedPrivateChatPeer != nil {
             // In private chat
-            if let peerNickname = meshService?.getPeerNicknames()[targetPeerID] {
+            if let peerNickname = meshService?.peerNickname(peerID: targetPeerID) {
                 let personalMessage = "* \(emoji) \(myNickname) \(action) you\(suffix) *"
                 meshService?.sendPrivateMessage(personalMessage, to: targetPeerID, 
                                                recipientNickname: peerNickname, 

bitchat/Services/NostrTransport.swift

@@ -31,6 +31,7 @@ final class NostrTransport: Transport {
     func emergencyDisconnectAll() { /* no-op */ }
 
     func isPeerConnected(_ peerID: String) -> Bool { false }
+    func peerNickname(peerID: String) -> String? { nil }
     func getPeerNicknames() -> [String : String] { [:] }
 
     func getFingerprint(for peerID: String) -> String? { nil }

bitchat/Services/PrivateChatManager.swift

@@ -53,7 +53,7 @@ class PrivateChatManager: ObservableObject {
     /// Send a private message
     func sendMessage(_ content: String, to peerID: String) {
         guard let meshService = meshService,
-              let peerNickname = meshService.getPeerNicknames()[peerID] else {
+              let peerNickname = meshService.peerNickname(peerID: peerID) else {
             return
         }
         

bitchat/Services/Transport.swift

@@ -29,6 +29,7 @@ protocol Transport: AnyObject {
 
     // Connectivity and peers
     func isPeerConnected(_ peerID: String) -> Bool
+    func peerNickname(peerID: String) -> String?
     func getPeerNicknames() -> [String: String]
 
     // Protocol utilities

bitchat/Services/UnifiedPeerService.swift

@@ -279,7 +279,7 @@ class UnifiedPeerService: ObservableObject, TransportPeerEventsDelegate {
         
         if actualNickname.isEmpty {
             // Try to get from mesh service's current peer list
-            if let meshPeerNickname = meshService.getPeerNicknames()[peerID] {
+            if let meshPeerNickname = meshService.peerNickname(peerID: peerID) {
                 actualNickname = meshPeerNickname
                 SecureLogger.log("🔍 Got nickname from mesh service: '\(actualNickname)'", 
                                category: SecureLogger.session, level: .debug)