Fix: TextField gray overlay when iOS app runs on macOS

Issue: When the iOS app is downloaded from the Mac App Store and run on
Apple Silicon Macs, a gray overlay appears over TextField components when
Increase Contrast accessibility setting is disabled.

Reproduction:
1. Download bitchat iOS app from Mac App Store
2. Run on Apple Silicon Mac
3. Disable 'Increase Contrast' in System Settings > Accessibility > Display
4. Focus on text input field - gray overlay appears

Fix: Use ProcessInfo.processInfo.isiOSAppOnMac runtime detection to disable
autocorrection only when iOS app runs on macOS. This targets the exact
environment where the issue occurs while preserving normal autocorrection
behavior for iPhone/iPad users.

Addresses code review feedback about incorrect conditional compilation.

Author: SkinnnyJay

bitchat/Views/ContentView.swift

@@ -11,6 +11,20 @@ import SwiftUI
 import UIKit
 #endif
 
+#if os(iOS)
+@available(iOS 14.0, *)
+struct IOSOnMacFixModifier: ViewModifier {
+    func body(content: Content) -> some View {
+        if ProcessInfo.processInfo.isiOSAppOnMac {
+            content
+                .autocorrectionDisabled(true)
+        } else {
+            content
+        }
+    }
+}
+#endif
+
 // MARK: - Supporting Types
 
 //
@@ -815,6 +829,10 @@ struct ContentView: View {
                 .foregroundColor(textColor)
                 .focused($isTextFieldFocused)
                 .padding(.leading, 12)
+                #if os(iOS)
+                // Fix for gray overlay issue when iOS app runs on macOS with Increase Contrast disabled
+                .modifier(IOSOnMacFixModifier())
+                #endif
                 // iOS keyboard autocomplete and capitalization enabled by default
                 .onChange(of: messageText) { newValue in
                     // Cancel previous debounce timer