build: split the engine into liboakengine.so; worker drops the UI entirely

Physical split: app/{audio,cli,codec,common,config,node,pluginSupport,
render,task,timeline,undo,tool,shaders} plus coreengine, version and
ui/icons+colorcoding move to a new top-level engine/ tree, built as
liboakengine.so (shared). The render backends (oakgl/oakvulkan) move
with it and link the engine library instead of embedding a static
render-core subset (libolive-rendercore is gone).

- oak-render-worker now links liboakengine instead of the whole
  libolive-editor object set: 336MB -> 2.9MB, no Qt Widgets UI
- the editor links liboakengine for the engine and keeps only UI
  objects in libolive-editor
- install/packaging: GNUInstallDirs libdir on Linux, bundle copy on
  macOS, oakengine.dll staged for NSIS, AppImage validation entry
- fix backend lookup for the new layout: DynamicRenderer searched
  ../app but backends now live in engine/; a stale pre-split liboakgl
  in the build tree got dlopened instead, re-initialized and later
  destroyed the interposed engine statics (full-suite segfault at
  DialogSequenceParameterTab, found via gdb watchpoint)

engine/node/factory.h

@@ -0,0 +1,124 @@
+/***
+
+  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/>.
+
+***/
+
+#ifndef OAK_NODEFACTORY_H
+#define OAK_NODEFACTORY_H
+
+#include <QList>
+
+#include "node.h"
+
+namespace olive
+{
+
+class NodeFactory {
+public:
+	enum InternalID {
+		k_viewer_output,
+		k_clip_block,
+		k_gap_block,
+		k_polygon_generator,
+		k_matrix_generator,
+		k_transform_distort,
+		k_track_output,
+		k_audio_volume,
+		k_audio_panning,
+		k_math,
+		k_time,
+		k_trigonometry,
+		k_blur_filter,
+		k_solid_generator,
+		k_merge,
+		k_stroke_filter,
+		k_text_generator_v1,
+		k_text_generator_v2,
+		k_text_generator_v3,
+		k_cross_dissolve_transition,
+		k_dip_to_color_transition,
+		k_mosaic_filter,
+		k_crop_distort,
+		k_project_footage,
+		k_project_folder,
+		k_project_sequence,
+		k_value_node,
+		k_time_remap_node,
+		k_subtitle_block,
+		k_shape_generator,
+		k_color_difference_key_keying,
+		k_despill_keying,
+		k_group_node,
+		k_opacity_effect,
+		k_flip_distort,
+		k_noise_generator,
+		k_time_offset_node,
+		k_corner_pin_distort,
+		k_display_transform,
+		k_ocio_grading_transform_linear,
+		k_ocio_lut,
+		k_three_way_color,
+		k_chroma_key,
+		k_mask_distort,
+		k_drop_shadow_filter,
+		k_time_format,
+		k_wave_distort,
+		k_ripple_distort,
+		k_tile_distort,
+		k_swirl_distort,
+		k_multicam_node,
+		k_ocio_grading_transform_log,
+		k_white_balance,
+
+		// Count value
+		k_internal_node_count
+	};
+
+	NodeFactory() = default;
+
+	static void initialize();
+
+	static void destroy();
+
+	static QString get_name_from_id(const QString &id);
+
+	static Node *create_from_id(const QString &id);
+	static void register_plugin_nodes();
+
+	static Node *create_from_factory_index(const InternalID &id);
+
+	/**
+	 * @brief Access the internal node library
+	 *
+	 * Exposed for the UI layer (e.g. widget/menu/factorymenu), which builds
+	 * node creation menus from the library. The library itself stays
+	 * UI-independent.
+	 */
+	static const QList<Node *> &get_library()
+	{
+		return library;
+	}
+
+private:
+	static QList<Node *> library;
+};
+
+}
+
+#endif // OAK_NODEFACTORY_H