Add dev-qt from an older version of the gentoo repo

Qt5 has been removed, we restore it since we still use it.

dev-qt/qt3d/qt3d-6.8.3.ebuild

@@ -0,0 +1,36 @@
+# Copyright 2021-2025 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+inherit qt6-build
+
+DESCRIPTION="3D rendering module for the Qt6 framework"
+
+if [[ ${QT6_BUILD_TYPE} == release ]]; then
+	KEYWORDS="amd64 arm arm64 ~loong ~riscv x86"
+elif [[ ${QT6_BUILD_TYPE} == live ]]; then
+	EGIT_SUBMODULES=() # skip qtquick3d-assimp
+fi
+
+IUSE="gles2-only qml vulkan"
+
+RDEPEND="
+	~dev-qt/qtbase-${PV}:6[concurrent,gles2-only=,gui,network,opengl,vulkan=]
+	~dev-qt/qtshadertools-${PV}:6
+	media-libs/assimp:=
+	qml? ( ~dev-qt/qtdeclarative-${PV}:6 )
+"
+DEPEND="
+	${RDEPEND}
+	vulkan? ( dev-util/vulkan-headers )
+"
+
+src_configure() {
+	local mycmakeargs=(
+		$(cmake_use_find_package qml Qt6Qml)
+		-DQT_FEATURE_qt3d_system_assimp=ON
+	)
+
+	qt6-build_src_configure
+}