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/task/project/loadotio/loadotio.cpp

@@ -109,7 +109,7 @@ bool LoadOTIOTask::run()
 	// Generate a list of sequences with the same names as the timelines.
 	// Assumes each timeline has a unique name.
 	int unnamed_sequence_count = 0;
-	foreach (auto timeline, timelines) {
+	for (auto timeline : timelines) {
 		Sequence *sequence = new Sequence();
 		if (!timeline->name().empty()) {
 			sequence->set_label(QString::fromStdString(timeline->name()));
@@ -124,7 +124,7 @@ bool LoadOTIOTask::run()
 		timeline_sequnce_map.insert(timeline, sequence);
 
 		// Get number of clips for loading bar
-		foreach (auto track, timeline->tracks()->children()) {
+		for (auto track : timeline->tracks()->children()) {
 			auto otio_track = static_cast<OTIO::Track *>(track.value);
 			number_of_clips += otio_track->children().size();
 		}

engine/task/project/saveotio/saveotio.cpp

@@ -64,7 +64,7 @@ bool SaveOTIOTask::run()
 			serialized.push_back(otio_timeline);
 		} else {
 			// Delete all existing timelines
-			foreach (auto s, serialized) {
+			for (auto s : serialized) {
 				s->possibly_delete();
 			}
 
@@ -91,7 +91,7 @@ bool SaveOTIOTask::run()
 		collection->possibly_delete();
 
 		// Delete all existing timelines
-		foreach (auto s, serialized) {
+		for (auto s : serialized) {
 			s->possibly_delete();
 		}
 	}