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.

tests/gtest/dynamic_render_backend_test.cpp

@@ -22,6 +22,28 @@ TEST(DynamicRenderBackend, LoadsExperimentalOpenGLBackend)
 #endif
 }
 
+TEST(DynamicRenderBackend, LoadsExperimentalVulkanBackendWhenAvailable)
+{
+#ifndef OAK_ENABLE_DYNAMIC_RENDER_BACKEND
+	GTEST_SKIP() << "Dynamic render backend is not enabled in this build";
+#else
+	olive::DynamicRenderer renderer(QStringLiteral("vulkan"));
+	ASSERT_TRUE(renderer.Load());
+	OakRenderBackendInfo info = {};
+	ASSERT_TRUE(renderer.GetBackendInfo(&info));
+	if (info.kind != OAK_RENDER_BACKEND_VULKAN) {
+		GTEST_SKIP() << "Vulkan backend is not available on this system";
+	}
+	EXPECT_EQ(renderer.backend_name(), QStringLiteral("vulkan"));
+	EXPECT_EQ(renderer.OpenGLContext(), nullptr);
+	EXPECT_STREQ(info.name, "vulkan");
+	EXPECT_TRUE(info.capabilities & OAK_RENDER_BACKEND_CAP_TEXTURES);
+	EXPECT_TRUE(info.capabilities & OAK_RENDER_BACKEND_CAP_SHADERS);
+	EXPECT_TRUE(info.capabilities & OAK_RENDER_BACKEND_CAP_BLIT);
+	EXPECT_TRUE(info.capabilities & OAK_RENDER_BACKEND_CAP_READBACK);
+#endif
+}
+
 TEST(DynamicRenderBackend, FallsBackWhenExperimentalVulkanUnavailable)
 {
 #ifndef OAK_ENABLE_DYNAMIC_RENDER_BACKEND
@@ -29,10 +51,13 @@ TEST(DynamicRenderBackend, FallsBackWhenExperimentalVulkanUnavailable)
 #else
 	olive::DynamicRenderer renderer(QStringLiteral("vulkan"));
 	ASSERT_TRUE(renderer.Load());
-	EXPECT_EQ(renderer.backend_name(), QStringLiteral("opengl"));
-	EXPECT_EQ(renderer.OpenGLContext(), nullptr);
 	OakRenderBackendInfo info = {};
 	ASSERT_TRUE(renderer.GetBackendInfo(&info));
+	if (info.kind == OAK_RENDER_BACKEND_VULKAN) {
+		GTEST_SKIP() << "Vulkan backend is available on this system; skip fallback test";
+	}
+	EXPECT_EQ(renderer.backend_name(), QStringLiteral("opengl"));
+	EXPECT_EQ(renderer.OpenGLContext(), nullptr);
 	EXPECT_EQ(info.kind, OAK_RENDER_BACKEND_OPENGL);
 	EXPECT_STREQ(info.name, "opengl");
 #endif

tests/gtest/plugin_ofx_integration_test.cpp

@@ -119,7 +119,7 @@ TEST(PluginIntegration, ChromaKeyerCreateAndRender)
 	olive::plugin::PluginJob job(instance, nullptr, row);
 	olive::TexturePtr output = std::make_shared<olive::Texture>(params);
 
-	olive::plugin::PluginRenderer renderer;
+	olive::plugin::PluginRenderer renderer(nullptr);
 	renderer.RenderPlugin(input, job, output, params, true, false);
 
 	EXPECT_TRUE(output->frame());

tests/gtest/plugin_ofx_misc_test.cpp

@@ -190,7 +190,7 @@ bool RenderPlugin(const std::string &plugin_id,
 	PluginJob job(instance, nullptr, inputs);
 	TexturePtr output = std::make_shared<Texture>(params);
 	
-	PluginRenderer renderer;
+	PluginRenderer renderer(nullptr);
 	renderer.RenderPlugin(nullptr, job, output, params, true, false);
 	
 	bool has_frame = output->frame() != nullptr;