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/node.cpp

@@ -2386,14 +2386,14 @@ TimeRange Node::transform_time_to(TimeRange time, Node *target,
 	Node *from = this;
 	Node *to = target;
 
-	if (dir == k_transform_towards_input) {
+	if (dir == k_towards_input) {
 		std::swap(from, to);
 	}
 
 	std::list<NodeInput> path = find_path(from, to, path_index);
 
 	if (!path.empty()) {
-		if (dir == k_transform_towards_input) {
+		if (dir == k_towards_input) {
 			for (auto it = path.crbegin(); it != path.crend(); it++) {
 				const NodeInput &i = (*it);
 				time = i.node()->input_time_adjustment(i.input(), i.element(),
@@ -2614,7 +2614,7 @@ void Node::invalidate_from_keyframe_time_change()
 
 	// Invalidate entire area surrounding the keyframe (either where it currently is, or where it used to be before it
 	// was resorted in the if block above)
-	foreach (const TimeRange &r, invalidate_range) {
+	for (const TimeRange &r : invalidate_range) {
 		parameter_value_changed(key->key_track_ref().input(), r);
 	}