fix: CI - out-of-line Client ctor (incomplete Transport in unwind path), widen ISO timestamp buffer, drop nested comment token

Author: AnkleBreaker Cowork

src/client.cpp

@@ -64,6 +64,8 @@ std::string trim_trailing_slash(std::string value) {
 
 }  // namespace
 
+Client::Client() = default;
+
 Client::~Client() {
     try {
         stop_heartbeat();

src/client.h

@@ -34,7 +34,10 @@ class Transport;
  */
 class Client {
 public:
-    Client() = default;
+    // Both out-of-line (client.cpp): members hold unique_ptr<Transport> with
+    // Transport forward-declared, so the ctor's unwind path and the dtor must
+    // be emitted in a TU that sees the complete type.
+    Client();
     ~Client();
 
     Client(const Client &) = delete;

src/clock.cpp

@@ -44,7 +44,7 @@ std::string format_iso8601_utc_ms(std::int64_t ms_since_epoch) {
     const auto second = static_cast<int>((ms_of_day / 1'000) % 60);
     const auto millis = static_cast<int>(ms_of_day % 1'000);
 
-    char buffer[32] = {};
+    char buffer[64] = {};
     std::snprintf(buffer, sizeof(buffer), "%04lld-%02u-%02uT%02d:%02d:%02d.%03dZ",
                   static_cast<long long>(date.year), date.month, date.day, hour, minute, second,
                   millis);

src/payloads.h

@@ -18,7 +18,7 @@ namespace tombstone {
  * (`false` means "no log" per the server contract).
  */
 
-/** Schema maxima (src/lib/*-schema.ts in the Tombstone monorepo). */
+/** Schema maxima (the per-endpoint schema files under src/lib in the Tombstone monorepo). */
 namespace limits {
 constexpr std::size_t build_version = 64;
 constexpr std::size_t signature = 128;