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).

app/widget/timebased/timebasedview.cpp

@@ -215,7 +215,7 @@ void TimeBasedView::drawForeground(QPainter *painter, const QRectF &rect)
 	if (snapped_) {
 		painter->setPen(palette().text().color());
 
-		foreach (const Rational &r, snap_time_) {
+		for (const Rational &r : snap_time_) {
 			double x = time_to_scene(r);
 
 			painter->drawLine(x, rect.top(), x, rect.height());

app/widget/timebased/timebasedviewselectionmanager.h

@@ -405,7 +405,7 @@ public:
 				QRectF(rubberband_scene_start_, current).normalized();
 
 			selected_ = rubberband_preselected_;
-			foreach (const DrawnObject &kp, drawn_objects_) {
+			for (const DrawnObject &kp : drawn_objects_) {
 				if (scene_rect.intersects(kp.second)) {
 					select(kp.first);
 				}

app/widget/timebased/timebasedwidget.cpp

@@ -19,6 +19,7 @@
 
 ***/
 
+#include <utility>
 #include "timebasedwidget.h"
 
 #include <QInputDialog>
@@ -48,8 +49,8 @@ TimeBasedWidget::TimeBasedWidget(bool ruler_text_visible,
 								 bool ruler_cache_status_visible,
 								 QWidget *parent)
 	: TimelineScaledWidget(parent)
-	, viewer_node_(nullptr)
 	, bridge_(new EngineEventBridge(this))
+	, viewer_node_(nullptr)
 	, auto_max_scrollbar_(false)
 	, toggle_show_all_(false)
 	, auto_set_timebase_(true)
@@ -408,7 +409,7 @@ void TimeBasedWidget::connect_timeline_view(TimeBasedView *base)
 			&QScrollBar::setValue);
 
 	// Connect scrollbar to other scrollbars
-	for (TimeBasedView *other : qAsConst(timeline_views_)) {
+	for (TimeBasedView *other : std::as_const(timeline_views_)) {
 		connect(other->horizontalScrollBar(), &QScrollBar::valueChanged,
 				base->horizontalScrollBar(), &QScrollBar::setValue);
 		connect(base->horizontalScrollBar(), &QScrollBar::valueChanged,
@@ -1229,7 +1230,7 @@ bool TimeBasedWidget::snap_point(const std::vector<Rational> &start_times,
 
 	// Find all points at this movement
 	std::vector<Rational> snap_times;
-	foreach (const SnapData &d, potential_snaps) {
+	for (const SnapData &d : potential_snaps) {
 		if (d.movement == *movement) {
 			snap_times.push_back(d.time);
 		}