chore: comment cleanup pass ahead of open-sourcing

Removes leftover debug scaffolding (stray Console.WriteLine/NSLog traces,
dead nick_buf_ptr, a no-op --print-config flag now implemented for real),
fixes stale/misleading comments (channel passwords are no longer a "future
M5+" feature, a wrong cross-reference, a stale TlsContext::close() mention,
an incomplete BanRecord::subject_type doc, and a smoke test pointing at a
build/m1-dev preset that no longer exists), strips internal M1-M5 milestone
jargon from comments now that the roadmap is done, trims comments that just
restated the following line, and consolidates a few "why" explanations that
were duplicated 2-3 times in the same file.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

clients/windows/VoiceCat.Interop/Enums.cs

@@ -37,7 +37,7 @@ public enum VcConnectionState
     TlsHandshake = 2,
     Authenticating = 3,
     Connected = 4,
-    /// <summary>M4: handshake succeeded, waiting on vc_confirm_server_identity().</summary>
+    /// <summary>Handshake succeeded, waiting on vc_confirm_server_identity().</summary>
     VerifyingIdentity = 5,
 }
 
@@ -84,13 +84,13 @@ public enum VcEventType
     TalkState = 9,
     Error = 10,
     Disconnected = 11,
-    /// <summary>M4: reply to VoiceCatClient.JoinChannelAsync's underlying vc_join_channel.</summary>
+    /// <summary>Reply to VoiceCatClient.JoinChannelAsync's underlying vc_join_channel.</summary>
     JoinResult = 12,
-    /// <summary>M4: the TOFU server-identity gate — see VcTofuStatus.</summary>
+    /// <summary>The TOFU server-identity gate — see VcTofuStatus.</summary>
     ServerIdentity = 13,
-    /// <summary>M5: async result for moderation/admin/channel operations.</summary>
+    /// <summary>Async result for moderation/admin/channel operations.</summary>
     GenericResult = 14,
-    /// <summary>M5: reply to VoiceCatClient.RequestAccountList — call ListAccounts() to read.</summary>
+    /// <summary>Reply to VoiceCatClient.RequestAccountList — call ListAccounts() to read.</summary>
     AccountList = 15,
     /// <summary>Voice-plane subscription state. u32a = 1 (subscribed) or 0 (unsubscribed).</summary>
     VoiceState = 16,