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/impl/logging.h

@@ -0,0 +1,32 @@
+// Copyright 2019 The Chromium Authors
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef PLATFORM_IMPL_LOGGING_H_
+#define PLATFORM_IMPL_LOGGING_H_
+
+#include <string>
+
+#include "util/osp_logging.h"
+
+namespace openscreen {
+
+// Append logging output to a named FIFO having the given `filename`. If the
+// file does not exist, an attempt is made to auto-create it. If unsuccessful,
+// abort the program. If this is never called, logging continues to output to
+// the default destination (stderr).
+void SetLogFifoOrDie(const char* filename);
+
+// Set the global logging level. If this is never called, kWarning is the
+// default.
+void SetLogLevel(LogLevel level);
+
+// Returns the current global logging level.
+LogLevel GetLogLevel();
+
+// Log a trace message. Used by the text trace logging platform.
+void LogTraceMessage(const std::string& message);
+
+}  // namespace openscreen
+
+#endif  // PLATFORM_IMPL_LOGGING_H_