feat(render): dynamic OpenGL/Vulkan backend split and backend-neutral viewer

- Extract libolive-rendercore static library to minimize backend link boundary.
- Add DynamicRenderer adapter with C ABI (oakgl/oakvulkan shared libs).
- Make OAK_ENABLE_DYNAMIC_RENDER_BACKEND default ON with OpenGL fallback.
- Implement VulkanRenderer prototype (textures, shaders, UBO blit, readback).
- Add backend-neutral viewer readback path (offscreen -> QImage -> QPainter).
- Refactor PluginRenderer to be renderer-agnostic; OFX plugins fall back to CPU
  path on non-OpenGL backends while preserving OpenGL render path.
- Add Renderer::AttachOutputTexture/DetachOutputTexture and C ABI forwards.
- Update docs/zh/render-backend-dynamic-plan.md for Phase 3/4/5.

.github/workflows/cd.yml

@@ -38,6 +38,8 @@ jobs:
             mingw-w64-ucrt-x86_64-fmt
             mingw-w64-ucrt-x86_64-expat
             mingw-w64-ucrt-x86_64-portaudio
+            mingw-w64-ucrt-x86_64-vulkan-headers
+            mingw-w64-ucrt-x86_64-vulkan-loader
             mingw-w64-ucrt-x86_64-nsis
             mingw-w64-ucrt-x86_64-ntldd
 
@@ -91,7 +93,7 @@ jobs:
       - name: Install dependencies
         run: |
           brew update
-          brew install cmake ninja pkg-config qt@6 ffmpeg openimageio opencolorio openexr portaudio expat dylibbundler
+          brew install cmake ninja pkg-config qt@6 ffmpeg openimageio opencolorio openexr portaudio expat molten-vk vulkan-headers dylibbundler
 
       - name: Build OpenTimelineIO
         run: |
@@ -261,7 +263,7 @@ jobs:
             qt6-base-dev qt6-base-dev-tools qt6-base-private-dev qt6-tools-dev qt6-tools-dev-tools \
             libavcodec-dev libavformat-dev libavutil-dev libswscale-dev libswresample-dev libavfilter-dev \
             libopencolorio-dev libopenimageio-dev libopenexr-dev libexpat1-dev \
-            portaudio19-dev libgl1-mesa-dev libxkbcommon-dev \
+            portaudio19-dev libgl1-mesa-dev libvulkan-dev vulkan-headers libxkbcommon-dev \
             wget fuse3 desktop-file-utils
 
       - name: Build