Add private messaging to managed macOS client

docs/porting-to-dotnet.md

@@ -853,7 +853,8 @@ build produced.
 **Checkpoint (2026-09-16):** `clients/apple/dotnet/VoiceCat.Mac` is a separate .NET 10
 AppKit application that consumes `VoiceCat.Core` directly. It implements guest and account
 connection, validated saved server profiles whose JSON never contains passwords,
-interactive TOFU approval, protected-channel password prompts, channel browsing, roster/chat,
+interactive TOFU approval, protected-channel password prompts, channel browsing, roster,
+channel/private text,
 voice subscription, native accessibility labels and default-device microphone/playback.
 Account passwords can be stored in macOS Keychain after successful authentication and are
 removed when the user disables remembering or deletes the profile.
@@ -864,7 +865,7 @@ not allocate, lock or block. Voice stream lifetime follows subscription, disconn
 channel changes. Current Apple API calls compile warning-free against Microsoft's
 26.4.10259 macOS reference assembly, and a macOS CI job builds the native codec/DSP shim and
 Apple solution. A real macOS device run and listen test remain required. The existing Swift
-app remains the release client until selectable devices, the rest of the moderation/settings
+app remains the release client until selectable devices and the moderation/settings
 surface, ScreenCaptureKit, VoiceOver
 validation, signing and notarization are complete.