Improve code organization and documentation (#325)

* Add MARK headers to improve code organization in major files

* Reorganize peer management functions in BluetoothMeshService

- Removed duplicate getCurrentPeerID(for:) function
- Consolidated peer identity functions in Peer Identity Mapping section
- Moved getPeerFingerprint(), getFingerprint(for:), isPeerIDOurs() to proper location
- Moved getCurrentPeerIDForFingerprint() and getCurrentPeerIDs() from Message Sending section
- Moved notifyPeerIDChange() to Peer Management section

* Consolidate peer management functions in BluetoothMeshService

- Moved getCachedPublicKey() and getCachedSigningKey() from Identity Cache Methods to Peer Connection Management
- Moved getPeerNicknames() and getPeerRSSI() to Peer Connection Management section
- Moved getAllConnectedPeerIDs(), notifyPeerListUpdate(), and cleanupStalePeers() to Peer Connection Management
- Removed duplicate function declarations after consolidation
- Improved code organization by grouping all peer-related functions together

* Consolidate message handling functions in ChatViewModel

- Moved handleHandshakeRequest() from floating location to Message Reception section
- Moved trimMessagesIfNeeded() and trimPrivateChatMessagesIfNeeded() to Message Batching section
- Improved code organization by grouping related message handling functions together
- Removed unnecessary comments from trim functions

* Improve ContentView organization with better documentation

- Added descriptive comments for complex inline computations
- Documented message extraction logic for private vs public chats
- Documented peer data computation and sorting logic
- Improved code readability by explaining complex operations inline
- Note: Attempted to extract complex computations into helper functions, but SwiftUI scope limitations made inline documentation a better approach

---------

Co-authored-by: jack <jackjackbits@users.noreply.github.com>

bitchat/Protocols/BitchatProtocol.swift

@@ -9,6 +9,8 @@
 import Foundation
 import CryptoKit
 
+// MARK: - Message Padding
+
 // Privacy-preserving padding utilities
 struct MessagePadding {
     // Standard block sizes for padding
@@ -75,6 +77,8 @@ struct MessagePadding {
     }
 }
 
+// MARK: - Message Types
+
 enum MessageType: UInt8 {
     case announce = 0x01
     case leave = 0x03
@@ -127,6 +131,8 @@ enum MessageType: UInt8 {
     }
 }
 
+// MARK: - Handshake State
+
 // Lazy handshake state tracking
 enum LazyHandshakeState {
     case none                    // No session, no handshake attempted
@@ -136,11 +142,15 @@ enum LazyHandshakeState {
     case failed(Error)         // Handshake failed
 }
 
+// MARK: - Special Recipients
+
 // Special recipient ID for broadcast messages
 struct SpecialRecipients {
     static let broadcast = Data(repeating: 0xFF, count: 8)  // All 0xFF = broadcast
 }
 
+// MARK: - Core Protocol Structures
+
 struct BitchatPacket: Codable {
     let version: UInt8
     let type: UInt8
@@ -197,6 +207,8 @@ struct BitchatPacket: Codable {
     }
 }
 
+// MARK: - Delivery Acknowledgments
+
 // Delivery acknowledgment structure
 struct DeliveryAck: Codable {
     let originalMessageID: String
@@ -287,6 +299,8 @@ struct DeliveryAck: Codable {
     }
 }
 
+// MARK: - Read Receipts
+
 // Read receipt structure
 struct ReadReceipt: Codable {
     let originalMessageID: String
@@ -371,6 +385,8 @@ struct ReadReceipt: Codable {
     }
 }
 
+// MARK: - Handshake Requests
+
 // Handshake request for pending messages
 struct HandshakeRequest: Codable {
     let requestID: String
@@ -1031,6 +1047,8 @@ struct VersionAck: Codable {
     }
 }
 
+// MARK: - Delivery Status
+
 // Delivery status for messages
 enum DeliveryStatus: Codable, Equatable {
     case sending
@@ -1058,6 +1076,8 @@ enum DeliveryStatus: Codable, Equatable {
     }
 }
 
+// MARK: - Message Model
+
 class BitchatMessage: Codable {
     let id: String
     let sender: String
@@ -1120,6 +1140,8 @@ extension BitchatMessage: Equatable {
     }
 }
 
+// MARK: - Delegate Protocol
+
 protocol BitchatDelegate: AnyObject {
     func didReceiveMessage(_ message: BitchatMessage)
     func didConnectToPeer(_ peerID: String)