build/ci: green builds and tests on all three platforms

Compiler hygiene (all platforms):
- Silence warnings across the tree: missing override, -Wreorder ctor
  init, -Wshadow, -Wsign-compare, missing switch cases, unused
  functions/captures, Qt 6.11 deprecations (QMouseEvent/QDropEvent
  accessors, qAsConst, Q_FOREACH over non-shared containers,
  AA_UseHighDpiPixmaps) and the .bak/ backup tree removal.
- Fix regressions from the cleanup: missing clip decls in
  capi/timeline.cpp, plugin.cpp rename fallout, panel setFocus
  ambiguity, QGraphicsItem::pos vs event->position(), duplicate
  k_push_button case, boolean test variable.

Windows:
- Qt portability: CommandLineParser is_set/add_option, QTimeZone
  systemTimeZone (QTimeZone::LocalTime is 6.11-only), k_progress_* enum.
- Linking: stop adding oakengine to OLIVE_LIBRARIES (import lib plus
  oakengine-obj caused multiple definitions); add OAKENGINE_STATIC so
  internal consumers no longer reference __imp_* stubs.
- oakengine.ver: export olive::Renderer typeinfo so liboakgl.so can be
  dlopened (Linux), DynamicRenderer no longer dlcloses backend libraries
  (crash in RenderManager's dtor calling into unmapped memory).
- OTIO runtime: copy DLLs next to every binary on Windows instead of
  relying on PATH (0xc0000135 in gtest discovery).
- Headless GL: the runner only has GDI OpenGL 1.1, killing every render
  worker. Deploy Mesa llvmpipe as opengl32sw.dll (Qt's software-GL
  channel) with QT_OPENGL=software, and let QT_OPENGL override the
  AA_UseDesktopOpenGL default. ExportTask fails fast after 8 consecutive
  undelivered frames instead of segfaulting or grinding forever;
  FFmpegEncoder::write_frame tolerates null frames.
- Tests: GetTempPathA+PID temp dirs, GetLongPathNameA for 8.3 names,
  forward-slash normalization when comparing project filenames.

Linux:
- Install libshaderc-dev so oakvulkan compiles GLSL (Vulkan tests).
- Accept UNORM floor-or-round (63/64) in the blit ping-pong test.
- Skip MainWindow construction test on the offscreen QPA (cannot paint
  QOpenGLWidget).

Also: oak_cli_transcode gets a 300s ctest timeout, worker logs GL
context version and LoadGraph/render_frame stages, and
docs/plans/eliminate-event-bridge-issues.md (English translation).

engine/node/project/footage/footage.cpp

@@ -377,8 +377,8 @@ void Footage::value(const NodeValueRow &value, const NodeGlobals &globals,
 					this, QStringLiteral("length"));
 
 		// Push each stream as a footage job
-		for (int i = 0; i < get_total_stream_count(); i++) {
-			Track::Reference ref = get_reference_from_real_index(i);
+		for (int si = 0; si < get_total_stream_count(); si++) {
+			Track::Reference ref = get_reference_from_real_index(si);
 			FootageJob job(globals.time(), decoder_, filename(), ref.type(),
 						   get_length(), globals.loop_mode());
 
@@ -427,9 +427,10 @@ void Footage::value(const NodeValueRow &value, const NodeGlobals &globals,
 						ProxyManager::k_proxy_ready &&
 					ProxyManager::proxy_filename_has_audio(proxy_path_)) {
 					int audio_rank = 0;
-					for (int i = 0; i < get_total_stream_count(); i++) {
+					for (int sj = 0; sj < get_total_stream_count(); sj++) {
 						const Track::Reference other =
-							get_reference_from_real_index(i);
+							get_reference_from_real_index(sj);
+
 						if (other.type() == Track::k_audio &&
 							get_audio_params(other.index()).stream_index() <
 								ap.stream_index()) {
@@ -448,8 +449,8 @@ void Footage::value(const NodeValueRow &value, const NodeGlobals &globals,
 		// Media is offline: push a generated warning frame for each video
 		// stream so missing media is clearly visible in the timeline instead
 		// of a transparent/black hole. generate_frame() draws the slat.
-		for (int i = 0; i < get_total_stream_count(); i++) {
-			Track::Reference ref = get_reference_from_real_index(i);
+		for (int si = 0; si < get_total_stream_count(); si++) {
+			Track::Reference ref = get_reference_from_real_index(si);
 			if (ref.type() != Track::k_video) {
 				continue;
 			}

engine/node/project/serializer/serializedlayoutinfo.cpp

@@ -28,7 +28,7 @@ void SerializedLayoutInfo::to_xml(QXmlStreamWriter *writer) const
 
 	writer->writeStartElement(QStringLiteral("folders"));
 
-	foreach (Folder *folder, open_folders) {
+	for (Folder *folder : open_folders) {
 		writer->writeTextElement(
 			QStringLiteral("folder"),
 			QString::number(reinterpret_cast<quintptr>(folder)));
@@ -38,7 +38,7 @@ void SerializedLayoutInfo::to_xml(QXmlStreamWriter *writer) const
 
 	writer->writeStartElement(QStringLiteral("timeline"));
 
-	foreach (Sequence *sequence, open_sequences) {
+	for (Sequence *sequence : open_sequences) {
 		writer->writeTextElement(
 			QStringLiteral("sequence"),
 			QString::number(reinterpret_cast<quintptr>(sequence)));
@@ -48,7 +48,7 @@ void SerializedLayoutInfo::to_xml(QXmlStreamWriter *writer) const
 
 	writer->writeStartElement(QStringLiteral("viewers"));
 
-	foreach (ViewerOutput *viewer, open_viewers) {
+	for (ViewerOutput *viewer : open_viewers) {
 		writer->writeTextElement(
 			QStringLiteral("viewer"),
 			QString::number(reinterpret_cast<quintptr>(viewer)));