Implement Cast Streaming mirroring, DLNA casting, daemon+GUI, and breadd integration

Builds out the full v1 scope: a vendored+patched openscreen subset for
low-latency Cast Streaming (Mirroring receiver 0F5096E8) alongside the
existing Cast V2/HLS and new DLNA/AVTransport casting paths, breadcastd's
Idle/Casting state machine with a private IPC socket, the breadcast GTK4
popup as a thin IPC client, and bread.cast.*/bread.command.cast.* breadd
integration (device discovery, start/stop, mirroring lifecycle events).
Also adds bakery/systemd/Forgejo CI packaging.

Validated end-to-end against a real Chromecast/Google TV: negotiated
Cast Streaming session, live pipeline playback, and daemon+GUI click-to-cast/
stop through the actual popup.

breadcast-caststream-sys/vendor/openscreen/platform/api/trace_event.cc

@@ -0,0 +1,61 @@
+// Copyright 2022 The Chromium Authors
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "platform/api/trace_event.h"
+
+#include <sstream>
+
+namespace openscreen {
+
+TraceEvent::TraceEvent(TraceCategory category,
+                       Clock::time_point start_time,
+                       const char* name,
+                       const char* file_name,
+                       uint32_t line_number)
+    : category(category),
+      start_time(start_time),
+      name(name),
+      file_name(file_name),
+      line_number(line_number) {}
+
+TraceEvent::TraceEvent() = default;
+TraceEvent::TraceEvent(TraceEvent&&) noexcept = default;
+TraceEvent::TraceEvent(const TraceEvent&) = default;
+TraceEvent& TraceEvent::operator=(TraceEvent&&) = default;
+TraceEvent& TraceEvent::operator=(const TraceEvent&) = default;
+TraceEvent::~TraceEvent() = default;
+
+std::string TraceEvent::ToString() const {
+  std::ostringstream oss;
+
+  oss << ids << " " << openscreen::ToString(category) << "::" << name << " <"
+      << file_name << ":" << line_number << ">";
+
+  // We only support two arguments in total.
+  if (!arguments.empty()) {
+    oss << " { " << arguments[0].first << ": " << arguments[0].second;
+    if (arguments.size() > 1) {
+      oss << ", " << arguments[1].first << ": " << arguments[1].second;
+    }
+    oss << " }";
+  }
+  return oss.str();
+}
+
+void TraceEvent::TruncateStrings() {
+  for (auto& argument : arguments) {
+    if (argument.second.size() > kMaxStringLength) {
+      argument.second.resize(kMaxStringLength);
+      // Populate last three digits with ellipses to indicate that
+      // we truncated this string.
+      argument.second.replace(kMaxStringLength - 3, 3, "...");
+    }
+  }
+}
+
+std::ostream& operator<<(std::ostream& out, const TraceEvent& event) {
+  return out << event.ToString();
+}
+
+}  // namespace openscreen