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/apple/Sources/VoiceCatCore/Enums.swift

@@ -61,7 +61,7 @@ public enum VoiceCatConnectionState: UInt32, Sendable, Equatable {
     case tlsHandshake = 2
     case authenticating = 3
     case connected = 4
-    /// M4: handshake succeeded, waiting on `confirmServerIdentity()`.
+    /// Handshake succeeded, waiting on `confirmServerIdentity()`.
     case verifyingIdentity = 5
 
     public init(_ cValue: vc_connection_state) {
@@ -125,13 +125,13 @@ public enum VoiceCatEventType: UInt32, Sendable, Equatable {
     case talkState = 9
     case error = 10
     case disconnected = 11
-    /// M4: reply to `joinChannel()` — see `VoiceCatEvent.result` / `.channelId`.
+    /// Reply to `joinChannel()` — see `VoiceCatEvent.result` / `.channelId`.
     case joinResult = 12
-    /// M4: the TOFU server-identity gate — see `VoiceCatEvent.tofuStatus` / `.text`.
+    /// The TOFU server-identity gate — see `VoiceCatEvent.tofuStatus` / `.text`.
     case serverIdentity = 13
-    /// M5: async result for moderation/admin/channel operations.
+    /// Async result for moderation/admin/channel operations.
     case genericResult = 14
-    /// M5: reply to `requestAccountList()` — call `listAccounts()` to read.
+    /// Reply to `requestAccountList()` — call `listAccounts()` to read.
     case accountList = 15
     /// Voice-plane subscription state. `u32a` = 1 (subscribed) or 0 (unsubscribed).
     case voiceState = 16