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/cast/streaming/impl/statistics_dispatcher.h

@@ -0,0 +1,58 @@
+// Copyright 2025 The Chromium Authors
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CAST_STREAMING_IMPL_STATISTICS_DISPATCHER_H_
+#define CAST_STREAMING_IMPL_STATISTICS_DISPATCHER_H_
+
+#include <vector>
+
+#include "cast/streaming/impl/statistics_common.h"
+#include "platform/api/time.h"
+#include "platform/base/span.h"
+#include "util/raw_ref.h"
+
+namespace openscreen::cast {
+
+class StatisticsCollector;
+class Environment;
+struct EncodedFrame;
+struct RtcpReceiverFrameLogMessage;
+
+// This class is responsible for dispatching statistics events.
+class StatisticsDispatcher {
+ public:
+  explicit StatisticsDispatcher(Environment& environment);
+
+  StatisticsDispatcher(const StatisticsDispatcher&) = delete;
+  StatisticsDispatcher& operator=(const StatisticsDispatcher&) = delete;
+  StatisticsDispatcher(StatisticsDispatcher&&) noexcept = delete;
+  StatisticsDispatcher& operator=(StatisticsDispatcher&&) = delete;
+  ~StatisticsDispatcher();
+
+  // Dispatches enqueue events for a given frame.
+  void DispatchEnqueueEvents(StreamType stream_type, const EncodedFrame& frame);
+
+  // Dispatches frame log messages.
+  void DispatchFrameLogMessages(
+      StreamType stream_type,
+      const std::vector<RtcpReceiverFrameLogMessage>& messages);
+
+  // Dispatches an ack event.
+  void DispatchAckEvent(StreamType stream_type,
+                        RtpTimeTicks rtp_timestamp,
+                        FrameId frame_id);
+
+  // Dispatches a frame dropped by encoder event.
+  void DispatchFrameDropEvent(StreamType stream_type,
+                              FrameId frame_id,
+                              RtpTimeTicks rtp_timestamp,
+                              Clock::time_point drop_time);
+
+ private:
+  const raw_ref<Environment> environment_;
+};
+
+}  // namespace openscreen::cast
+
+#endif  // CAST_STREAMING_IMPL_STATISTICS_DISPATCHER_H_