Prepare for App Store submission

- Added public domain headers to all test files
- Updated Info.plist with required App Store keys:
  - ITSAppUsesNonExemptEncryption = NO
  - LSApplicationCategoryType = Social Networking
  - UIRequiresFullScreen = YES
- Created proper Assets.xcassets structure
- Configured AppIcon.appiconset with all icon references
- Removed last TODO comment
- Created comprehensive App Store submission checklist
- Updated project.yml to include Assets.xcassets

The app is now ready for App Store submission. All debug code has been removed,
icons are configured, and privacy/security compliance is documented.

bitchatTests/BinaryProtocolTests.swift

@@ -1,3 +1,11 @@
+//
+// BinaryProtocolTests.swift
+// bitchatTests
+//
+// This is free and unencumbered software released into the public domain.
+// For more information, see <https://unlicense.org>
+//
+
 import XCTest
 @testable import bitchat
 

bitchatTests/BitchatMessageTests.swift

@@ -1,3 +1,11 @@
+//
+// BitchatMessageTests.swift
+// bitchatTests
+//
+// This is free and unencumbered software released into the public domain.
+// For more information, see <https://unlicense.org>
+//
+
 import XCTest
 @testable import bitchat
 

bitchatTests/BloomFilterTests.swift

@@ -1,3 +1,11 @@
+//
+// BloomFilterTests.swift
+// bitchatTests
+//
+// This is free and unencumbered software released into the public domain.
+// For more information, see <https://unlicense.org>
+//
+
 import XCTest
 @testable import bitchat
 

bitchatTests/MessagePaddingTests.swift

@@ -1,3 +1,11 @@
+//
+// MessagePaddingTests.swift
+// bitchatTests
+//
+// This is free and unencumbered software released into the public domain.
+// For more information, see <https://unlicense.org>
+//
+
 import XCTest
 @testable import bitchat