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.

app/render/interlacetexture.cpp

@@ -0,0 +1,59 @@
+/***
+
+  Olive - Non-Linear Video Editor
+  Copyright (C) 2022 Olive Team
+  Modifications Copyright (C) 2025 mikesolar
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#include "renderer.h"
+
+#include "common/filefunctions.h"
+#include "node/value.h"
+#include "render/job/shaderjob.h"
+
+namespace olive
+{
+
+TexturePtr Renderer::InterlaceTexture(TexturePtr top, TexturePtr bottom,
+									  const VideoParams &params)
+{
+	color_cache_mutex_.lock();
+	if (interlace_texture_.isNull()) {
+		interlace_texture_ =
+			CreateNativeShader(ShaderCode(FileFunctions::ReadFileAsString(
+				QStringLiteral(":/shaders/interlace.frag"))));
+	}
+	color_cache_mutex_.unlock();
+
+	ShaderJob job;
+	job.Insert(QStringLiteral("top_tex_in"),
+			   NodeValue(NodeValue::kTexture, QVariant::fromValue(top)));
+	job.Insert(QStringLiteral("bottom_tex_in"),
+			   NodeValue(NodeValue::kTexture, QVariant::fromValue(bottom)));
+	job.Insert(QStringLiteral("resolution_in"),
+			   NodeValue(NodeValue::kVec2,
+						 QVector2D(params.effective_width(),
+								   params.effective_height())));
+
+	TexturePtr output = CreateTexture(params);
+
+	BlitToTexture(interlace_texture_, job, output.get());
+
+	return output;
+}
+
+}