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>

tools/voicecat-admin/src/main.cpp

@@ -39,7 +39,6 @@ int main(int argc, char** argv) {
     std::string data_dir = "voicecat-data";
     int i = 1;
 
-    // Parse --data-dir
     if (i < argc && std::strcmp(argv[i], "--data-dir") == 0) {
         if (++i >= argc) { std::fprintf(stderr, "Missing argument to --data-dir\n"); return 1; }
         data_dir = argv[i++];
@@ -48,7 +47,7 @@ int main(int argc, char** argv) {
     if (i >= argc || std::strcmp(argv[i], "account") != 0) {
         print_usage(argv[0]); return 1;
     }
-    ++i;  // skip "account"
+    ++i;
 
     if (i >= argc) { print_usage(argv[0]); return 1; }
     std::string subcmd = argv[i++];