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>

core/src/protocol/protocol.h

@@ -6,10 +6,9 @@
  * request_id ↔ response, and dispatches to handlers. Media frames do NOT come through here
  * (they use the fixed binary header in voice.md §2).
  *
- * STATUS: real. Protobuf codegen is on (core/CMakeLists.txt) for VOICECAT_HAS_NET builds
- * (`dev`/`release`/`server-release`); FrameCodec below is fully implemented and used by both the
- * client (net/transport.h) and the server (conn_session.cpp). See protocol/envelope.h for the
- * Envelope-level encode/decode that sits on top of this.
+ * FrameCodec below is used by both the client (net/transport.h) and the server
+ * (conn_session.cpp). See protocol/envelope.h for the Envelope-level encode/decode that sits
+ * on top of this.
  */
 #ifndef VOICECAT_PROTOCOL_PROTOCOL_H
 #define VOICECAT_PROTOCOL_PROTOCOL_H