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/valuedatabase.h

@@ -0,0 +1,89 @@
+/***
+
+  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_NODEVALUEDATABASE_H
+#define OAK_NODEVALUEDATABASE_H
+
+#include "param.h"
+#include "value.h"
+
+namespace olive
+{
+
+class NodeValueDatabase {
+public:
+	NodeValueDatabase() = default;
+
+	NodeValueTable &operator[](const QString &input_id)
+	{
+		return tables_[input_id];
+	}
+
+	void insert(const QString &key, const NodeValueTable &value)
+	{
+		tables_.insert(key, value);
+	}
+
+	NodeValueTable take(const QString &key)
+	{
+		return tables_.take(key);
+	}
+
+	NodeValueTable merge() const;
+
+	using Tables = QHash<QString, NodeValueTable>;
+	using const_iterator = Tables::const_iterator;
+	using iterator = Tables::iterator;
+
+	inline const_iterator cbegin() const
+	{
+		return tables_.cbegin();
+	}
+
+	inline const_iterator cend() const
+	{
+		return tables_.cend();
+	}
+
+	inline iterator begin()
+	{
+		return tables_.begin();
+	}
+
+	inline iterator end()
+	{
+		return tables_.end();
+	}
+
+	inline bool contains(const QString &s) const
+	{
+		return tables_.contains(s);
+	}
+
+private:
+	Tables tables_;
+};
+
+}
+
+Q_DECLARE_METATYPE(olive::NodeValueDatabase)
+
+#endif // OAK_NODEVALUEDATABASE_H