packaging: ship the Vulkan backend on all platforms, standard lib layout

- Linux CD builds no longer disable Vulkan: the AppImage, deb, rpm and
  Arch packages now build and ship liboakvulkan (the AppImage deploys
  it via linuxdeploy --library so libvulkan is bundled too, and the
  verify step checks both backend libraries); deb/rpm dependencies gain
  libvulkan1/vulkan-loader; the Arch PKGBUILD gains vulkan-headers
- macOS CD installs vulkan-loader and exports VULKAN_SDK so
  find_package(Vulkan) locates the Homebrew loader (previously the
  Vulkan backend silently never built there)
- ffmpeg_bridge now installs to the standard lib directory with
  /../lib RPATH instead of the non-standard ffmpeg_bridge/bin
  layout (verified: editor, worker, oakgl and oakvulkan all resolve it)
- build guides (EN/ZH) document the macOS Vulkan backend dependencies
  and the VULKAN_SDK variable

docs/build.md

@@ -208,7 +208,7 @@ Install dependencies:
 
 ```bash
 brew update
-brew install cmake ninja pkg-config qt@6 ffmpeg openimageio opencolorio openexr portaudio expat molten-vk vulkan-headers
+brew install cmake ninja pkg-config qt@6 ffmpeg openimageio opencolorio openexr portaudio expat molten-vk vulkan-headers vulkan-loader
 ```
 
 Build OpenTimelineIO (optional, required for OTIO support):
@@ -231,6 +231,9 @@ export PATH="$(brew --prefix qt@6)/bin:$PATH"
 export CMAKE_PREFIX_PATH="$(brew --prefix qt@6)"
 export OTIO_LOCATION="${PWD}/otio-install"
 export OCIO_LOCATION="$(brew --prefix opencolorio)"
+# Let CMake's FindVulkan locate the Homebrew Vulkan loader (optional,
+# enables the Vulkan render backend)
+export VULKAN_SDK="$(brew --prefix vulkan-loader)"
 
 cmake -S . -B build -G Ninja -DBUILD_TESTS=ON -DBUILD_QT6=ON \
   -DOTIO_LOCATION="${OTIO_LOCATION}" \

docs/build_macos.md

@@ -66,7 +66,21 @@ brew install openimageio opencolorio openexr
 brew install portaudio expat
 ```
 
-### 7. Install Test Framework (Optional)
+### 7. Install Vulkan Backend Dependencies (Optional)
+
+Only needed for the Vulkan render backend. Oak builds the OpenGL backend regardless and falls back to it at runtime if Vulkan is unavailable:
+
+```bash
+brew install molten-vk vulkan-headers vulkan-loader
+```
+
+Point CMake at the loader so `find_package(Vulkan)` succeeds (add to `~/.zshrc` if you build regularly):
+
+```bash
+export VULKAN_SDK="$(brew --prefix vulkan-loader)"
+```
+
+### 8. Install Test Framework (Optional)
 
 Only needed if you plan to build and run tests:
 

docs/zh/build.md

@@ -208,7 +208,7 @@ macOS 现在是正式支持的平台。更详细的逐步指南请参见 [`build
 
 ```bash
 brew update
-brew install cmake ninja pkg-config qt@6 ffmpeg openimageio opencolorio openexr portaudio expat molten-vk vulkan-headers
+brew install cmake ninja pkg-config qt@6 ffmpeg openimageio opencolorio openexr portaudio expat molten-vk vulkan-headers vulkan-loader
 ```
 
 构建 OpenTimelineIO（可选，如需 OTIO 支持）：
@@ -231,6 +231,9 @@ export PATH="$(brew --prefix qt@6)/bin:$PATH"
 export CMAKE_PREFIX_PATH="$(brew --prefix qt@6)"
 export OTIO_LOCATION="${PWD}/otio-install"
 export OCIO_LOCATION="$(brew --prefix opencolorio)"
+# 让 CMake 的 FindVulkan 找到 Homebrew 的 Vulkan loader（可选，
+# 启用 Vulkan 渲染后端）
+export VULKAN_SDK="$(brew --prefix vulkan-loader)"
 
 cmake -S . -B build -G Ninja -DBUILD_TESTS=ON -DBUILD_QT6=ON \
   -DOTIO_LOCATION="${OTIO_LOCATION}" \

docs/zh/build_macos-zh.md

@@ -66,7 +66,21 @@ brew install openimageio opencolorio openexr
 brew install portaudio expat
 ```
 
-### 7. 安装测试框架（可选）
+### 7. 安装 Vulkan 后端依赖（可选）
+
+仅在需要 Vulkan 渲染后端时需要。Oak 始终构建 OpenGL 后端，当 Vulkan 不可用时会自动回退到它：
+
+```bash
+brew install molten-vk vulkan-headers vulkan-loader
+```
+
+让 CMake 能找到 loader，使 `find_package(Vulkan)` 成功（经常构建的话可以写入 `~/.zshrc`）：
+
+```bash
+export VULKAN_SDK="$(brew --prefix vulkan-loader)"
+```
+
+### 8. 安装测试框架（可选）
 
 仅在需要构建和运行测试时需要：