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/util/raw_ref.h

@@ -0,0 +1,122 @@
+// Copyright 2026 The Chromium Authors
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef UTIL_RAW_REF_H_
+#define UTIL_RAW_REF_H_
+
+#if defined(BUILD_WITH_CHROMIUM)
+
+#include "partition_alloc/pointers/raw_ref.h"  // nogncheck
+
+namespace openscreen {
+
+template <typename T>
+using raw_ref = ::base::raw_ref<T>;
+
+}  // namespace openscreen
+
+#else  // !defined(BUILD_WITH_CHROMIUM)
+
+#include <type_traits>
+#include <utility>
+
+#include "util/raw_ptr.h"
+
+namespace openscreen {
+
+template <typename T>
+class raw_ref;
+
+namespace internal {
+template <typename T>
+struct is_raw_ref : std::false_type {};
+
+template <typename T>
+struct is_raw_ref<raw_ref<T> > : std::true_type {};
+}  // namespace internal
+
+template <typename T>
+class OPENSCREEN_TRIVIAL_ABI raw_ref {
+ public:
+  OPENSCREEN_ALWAYS_INLINE constexpr explicit raw_ref(T& ref) noexcept
+      : ptr_(&ref) {}
+
+  template <typename U,
+            typename = std::enable_if_t<
+                !internal::is_raw_ref<std::decay_t<U> >::value &&
+                std::is_convertible_v<U&, T&> > >
+  OPENSCREEN_ALWAYS_INLINE constexpr explicit raw_ref(U& ref) noexcept
+      : ptr_(&ref) {}
+
+  OPENSCREEN_ALWAYS_INLINE constexpr raw_ref(const raw_ref& other) noexcept =
+      default;
+  OPENSCREEN_ALWAYS_INLINE constexpr raw_ref(raw_ref&& other) noexcept =
+      default;
+
+  template <typename U,
+            typename = std::enable_if_t<std::is_convertible_v<U&, T&> > >
+  OPENSCREEN_ALWAYS_INLINE constexpr raw_ref(const raw_ref<U>& other) noexcept
+      : ptr_(other.ptr_) {}
+
+  template <typename U,
+            typename = std::enable_if_t<std::is_convertible_v<U&, T&> > >
+  OPENSCREEN_ALWAYS_INLINE constexpr raw_ref(raw_ref<U>&& other) noexcept
+      : ptr_(std::move(other.ptr_)) {}
+
+  ~raw_ref() = default;
+
+  OPENSCREEN_ALWAYS_INLINE constexpr raw_ref& operator=(
+      const raw_ref& other) noexcept = default;
+  OPENSCREEN_ALWAYS_INLINE constexpr raw_ref& operator=(
+      raw_ref&& other) noexcept = default;
+
+  template <typename U,
+            typename = std::enable_if_t<std::is_convertible_v<U&, T&> > >
+  OPENSCREEN_ALWAYS_INLINE constexpr raw_ref& operator=(
+      const raw_ref<U>& other) noexcept {
+    ptr_ = other.ptr_;
+    return *this;
+  }
+
+  template <typename U,
+            typename = std::enable_if_t<std::is_convertible_v<U&, T&> > >
+  OPENSCREEN_ALWAYS_INLINE constexpr raw_ref& operator=(
+      raw_ref<U>&& other) noexcept {
+    ptr_ = std::move(other.ptr_);
+    return *this;
+  }
+
+  OPENSCREEN_ALWAYS_INLINE constexpr T& get() const noexcept { return *ptr_; }
+  OPENSCREEN_ALWAYS_INLINE constexpr T* operator->() const noexcept {
+    return ptr_.get();
+  }
+  OPENSCREEN_ALWAYS_INLINE constexpr T& operator*() const noexcept {
+    return *ptr_;
+  }
+
+  template <typename U>
+  OPENSCREEN_ALWAYS_INLINE friend constexpr bool operator==(
+      const raw_ref& lhs,
+      const raw_ref<U>& rhs) noexcept {
+    return lhs.ptr_ == rhs.ptr_;
+  }
+  template <typename U>
+  OPENSCREEN_ALWAYS_INLINE friend constexpr bool operator!=(
+      const raw_ref& lhs,
+      const raw_ref<U>& rhs) noexcept {
+    return lhs.ptr_ != rhs.ptr_;
+  }
+
+ private:
+  template <typename U>
+  friend class raw_ref;
+
+  raw_ptr<T> ptr_;
+};
+
+}  // namespace openscreen
+
+#endif  // !defined(BUILD_WITH_CHROMIUM)
+
+#endif  // UTIL_RAW_REF_H_